Isometric Exercise Research Articles

Students learn the features of using isometrical exercises as a pedagogical technology for the formation of the skills of intensive use of physical culture tools the modern period

The purpose of the work was to clarify the views of the authors on the preparation for a meaningful process of physical exercises of students of higher education through the methodical use of isometric exercises; an analysis of their use in various types of training process was carried out and the relevance of their use during physical education classes of students was emphasized. The authors reviewed modern publications on the organization of the educational process in extreme conditions of martial law and the use of physical culture tools in order to adapt to the stressful conditions of life in situations of air alarms, power outages and lack of communication. The novelty of the study should be considered the views proposed by the authors on the formation of the skills of the meaningful use of physical education tools and the focus on the relevance of the use of isometric exercises in the process of preparing students for independent classes. The conclusions emphasize that the preparation of students for the conscious use of physical culture means in the modern period should involve the introduction of a wide range of educational directions. The authors point out the role and significance, features of the use of isometric exercises in sports, health and psychophysical training and reveal the relevance for the process of forming students' skills to consciously and meaningfully use the means of physical culture.

Delayed neuromuscular fatigue recovery unveils reduced fatigue tolerance in elderly following maximal intermittent exercise.

The aim of the study was to assess the impact of aging on neuromuscular fatigue and recovery. Ten young (23.08 ± 1.43years) and older (61.19 ± 1.80years) males performed an intermittent maximal isometric exercise with the knee extensors followed by 27min of recovery. Maximal voluntary contraction (MVC), total work (W'), voluntary activation (VA), potentiated resting twitch (Ptw), and electromyography (EMG) were recorded and then analyzed. Peripheral and central fatigue following exercise were lower in old compared to young (- 29.99% vs. - 42.68% and - 14.55 vs. - 20.02%; P < 0.05, respectively). Despite old performing 50% less work, RMS/Mmax reduction was similar between old and young (- 26.46% vs. - 29.93%; P > 0.05, respectively). During the recovery period, our results showed that recovery of the MVC was impaired for old (14.93% for old vs. 30.66% for young) and still incomplete until 27min.VA increased significantly compared to post exercise after 1min only for young (P = 0.001), potentially affecting the recovery pattern of MVC during the early phase due to their significant correlation (r2 = 0.58, P = 0.01). Peripheral fatigue recovery was also lower for old (11.18% vs. 18.72%; P < 0.001), and both groups failed to recover their baseline value (both P < 0.005). The lower peripheral and central fatigue observed in elderly following exercise appears for the first instance as a fatigue resistance. However, the delayed neuromuscular recovery reveals instead a reduced fatigue tolerance reflecting age-related alteration within contractile properties and/or within central nervous system.

Multicenter randomized controlled trial of exercise in aortic dissection survivors: rationale, design, and initial hemodynamic data

Aims: There are currently no evidence-based guidelines for exercise after thoracic aortic dissection (TAD), leading to highly variable recommendations that frequently lead patients to restrict their physical activities. This multicenter randomized controlled trial was intended to evaluate the safety and efficacy of a moderate intensity guided exercise program for TAD survivors. Methods: Participants were eligible if they had a Type A or Type B dissection at least 90 days before enrollment and could attend two in-person study visits. The guided exercise circuit consisted of six aerobic, isotonic, or isometric exercises that participants continued at home with virtual follow-up sessions. The primary endpoint is the change in the composite anxiety and depression PROMIS-29 T-score at 12 months. Secondary endpoints include changes in grip strength, weight, 24-h ambulatory blood pressure, and arterial biomechanical properties measured by central arterial waveform analysis. Results: Preliminary analysis of the first 81 enrolled participants demonstrated that the guided exercise circuit was completed safely and was not associated with severe hypertension, injury, or adverse cardiovascular events. At enrollment, adverse central waveform or ABPM characteristics were prevalent and were significantly associated with exertional hypertension. Conclusions: Guided exercise is safe for aortic dissection survivors. Follow-up of enrolled participants will conclude in October 2024.

Protocol for physiotherapeutic management of home care for elderly patients with hip and knee osteoarthritis

Background: Lower body musculoskeletal disorders are problems that affect muscles, bones, joints, tendons, ligaments, and nerves of the lower limbs. Osteoarthritis of the hip and knee is a degenerative disease that affects the cartilage of the hip and knee joints. It causes pain, stiffness, and limited movement. Objective: to implement a physiotherapy management protocol for home care for the elderly with osteoarthritis of the hip and knee, to improve functional capacity. Methods: a study was carried out with a 12-week intervention guideline on 20 participants with a mean age of 72 years. Weight was measured with a scale (omron) and height with a stadiometer (seca) in order to obtain the value of the Body Mass Index (BMI). The exercise guide consists of three phases: the first includes isometric exercises; the second involves isotonic and resistance exercises; and, the third includes balance exercises, gait re-education, reintegration into activities of daily living, a study with initial and final assessment, and instruments to measure functional capacity. The Short Physical Performance Battery (SPPB) was used. It consists of three tests (balance, walking, sitting and standing). The manual dynamometer measures muscle strength in lower limbs and the visual scale measures the perception of pain in the hip and knee. Results: the physical exercise guideline in elderlies with hip and knee osteoarthritis improved functional capacity increased muscle-strength, and pain perception. Conclusions: the exercise protocol increases the functional capacity of the elderly with osteoarthritis of the hip and knee, presenting adequate control in the lower body.

The Erector Spinae Muscle, a Determining Factor in the Pathological Biomechanics of the Spine

Pathological biomechanics of adolescent idiopathic scoliosis is dominated by unilateral erector spinae stiffness. This leads to morpho pathological vertebral changes that aggravate the condition. Manual therapies can be used to correct the asymmetry of the stretch reflexes, and massage techniques can be used to improve the range of motion. Pain is an aggravating factor for biomechanical disorders and can be combated by myofascial techniques. To prevent scoliosis in adults, it is possible to tone the erector spinae muscles (deadlifts and their variations, exercises with free weights, arm and leg ergometer exercises, some aquatic exercises, Pilates isometric exercises performed on a stable surface). Keywords: spinal erector muscles, scoliosis prophylaxis

Sympathetic Overactivity and Parasympathetic Impairment in Type 2 Diabetes: An Analysis of Cardiovascular Autonomic Functions.

Background Cardiovascular autonomic dysregulation is a known complication of Type 2 diabetes mellitus (T2DM), characterized by dysregulation in heart rate (HR) and blood pressure (BP). These disruptions in cardiovascular autonomic control can significantly influence the morbidity and mortality associated with the disease. Objectives This study aims to investigate how T2DM affects cardiovascular autonomic functions by comparing responses in HR, BP, and specific autonomic function tests between a control group without diabetes and a study group with diabetes. The research questions focus on assessing HR variability, baroreflex sensitivity, and other autonomic parameters to determine the extent of cardiovascular autonomic dysregulation in diabetic patients. Methods This cross-sectional study involved 200 adults, divided equally between a control group (n = 100) and a T2DM study group (n = 100). The exclusion criteria included cardiovascular diseases and renal impairment. Data collection involved assessing baseline characteristics such as age and BMI. Cardiovascular measures, including HR, systolic blood pressure (SBP), and diastolic blood pressure (DBP), were recorded after a five-minute rest. Autonomic function tests assessed sympathetic and parasympathetic responses, including the cold pressor test and the isometric hand grip exercise test. The statistical analysis was conducted using IBMSPSSStatistics for Windows, Version 25 (Released 2017; IBM Corp., Armonk, New York, United States), focusing on independent t-tests to compare between groups, considering p-values <0.05 as significant. Potential confounding variables like age and BMI were accounted for in the analysis to ensure robust findings Results The study group showed a higher average BMI (28.95 ± 5.60) compared to the control group (26.50 ± 5.70) and an increased resting HR (74.20 ± 8.60 bpm vs. 69.30 ± 9.10 bpm). The SBP was slightly higher in the study group (115.00 ± 19.00 mmHg vs. 114.50 ± 8.90 mmHg), while the DBP was lower (71.50 ± 10.70 mmHg vs. 72.80 ± 6.70 mmHg). The autonomic function tests showed a smaller increase in SBP (106.80 ± 11.00 mmHg) and a larger increase in DBP (75.90 ± 8.30 mmHg) upon standing in the study group compared to controls. The cold pressor test indicated increased sympathetic activity in the study group, with significant rises in SBP (133.70 ± 10.30 mmHg) and DBP (83.40 ± 9.00 mmHg) compared to the control group (SBP: 114.31 ± 11.87 mmHg, DBP: 71.85 ± 8.67 mmHg). These findings demonstrate marked differences in cardiovascular autonomic responses between the groups. Conclusions This study demonstrates that T2DM significantly impacts cardiovascular autonomic functions, with diabetic patients showing altered HR and BP indicative of increased sympathetic and decreased parasympathetic activity. These autonomic dysfunctions may heighten cardiovascular risk in diabetic individuals. Our findings highlight the importance of monitoring and managing cardiovascular autonomic functions in diabetic patients to reduce their risk of cardiovascular complications. Further research should investigate the underlying mechanisms and the effectiveness of interventions to improve autonomic function in this population.

Blood pressure responses to handgrip exercise but not apnea or mental stress are enhanced in women with a recent history of preeclampsia.

Preeclampsia is a risk factor for future cardiovascular diseases. However, the mechanisms underlying this association remain unclear, limiting effective prevention strategies. Blood pressure responses to acute stimuli may reveal cardiovascular dysfunction not apparent at rest, identifying individuals at elevated cardiovascular risk. Therefore, we compared blood pressure responsiveness with acute stimuli between previously preeclamptic (PPE) women (34 ± 5 yr old, 13 ± 6 mo postpartum) and women following healthy pregnancies (Ctrl; 29 ± 3 yr old, 15 ± 4 mo postpartum). Blood pressure (finger photoplethysmography calibrated to manual sphygmomanometry-derived values; PPE: n = 12, Ctrl: n = 12) was assessed during end-expiratory apnea, mental stress, and isometric handgrip exercise protocols. Integrated muscle sympathetic nerve activity (MSNA) was assessed in a subset of participants (peroneal nerve microneurography; PPE: n = 6, Ctrl: n = 8). Across all protocols, systolic blood pressure (SBP) was higher in PPE than Ctrl (main effects of group all P < 0.05). Peak changes in SBP were stressor specific: peak increases in SBP were not different between PPE and Ctrl during apnea (8 ± 6 vs. 6 ± 5 mmHg, P = 0.32) or mental stress (9 ± 5 vs. 4 ± 7 mmHg, P = 0.06). However, peak exercise-induced increases in SBP were greater in PPE than Ctrl (11 ± 5 vs. 7 ± 7 mmHg, P = 0.04). MSNA was higher in PPE than Ctrl across all protocols (main effects of group all P < 0.05), and increases in peak MSNA were greater in PPE than Ctrl during apnea (44 ± 6 vs. 27 ± 14 burst/100 hb, P = 0.04) and exercise (25 ± 8 vs. 13 ± 11 burst/100 hb, P = 0.01) but not different between groups during mental stress (2 ± 3 vs. 0 ± 5 burst/100 hb, P = 0.41). Exaggerated pressor and sympathetic responses to certain stimuli may contribute to the elevated long-term risk for cardiovascular disease in PPE.NEW & NOTEWORTHY Women with recent histories of preeclampsia demonstrated higher systolic blood pressures across sympathoexcitatory stressors relative to controls. Peak systolic blood pressure reactivity was exacerbated in previously preeclamptic women during small muscle-mass exercises, although not during apneic or mental stress stimuli. These findings underscore the importance of assessing blood pressure control during a variety of experimental conditions in previously preeclamptic women to elucidate mechanisms that may contribute to their elevated cardiovascular disease risk.

Clinical Progression and Load Management For Proximal Hamstring Tendinopathy In A Long-Distance Runner: A Case Report.

The characteristics of Proximal Hamstring Tendinopathy (PHT) include deep, localized pain in the region of the ischial tuberosity. Chronic lesions are often found in long-distance runners. Compression of the tendon and shear force at its insertion at the ischial tuberosity during hip flexion/adduction is a key etiologic factor. The aim of this case report is to analyze the effectiveness of an exercise protocol with progression of tendon loading in PHT in an amateur runner, by assessing pain and functional capacity. The subject was a 30-year-old male runner. After participating in a 10km race, he experienced an insidious onset of deep buttock pain in the right ischial tuberosity. His pain was aggravated by running on sloped roads and prolonged sitting on hard surfaces, particularly while driving. The visual analog scale (VAS) for pain, the Puranen-Orave test (PO), the Bent-Knee stretch test (BK stretch), the supine plank test, the Victorian Institute of Sport Assessment-proximal hamstring tendons (VISA-H) questionnaire, and the sciatic nerve mobility (via the Slump test) were assessed. The intervention involved a 12-week progressive loading exercise program divided into four phases. The initial pain was reduced at 6 weeks of intervention and further decreased at 12 weeks (VAS from 7, to 5 and to 1). Function increased at 6 weeks and at 12 weeks (VISA-H from 23, to 53, to 80). Sciatic nerve mobility was normal. The progression of training in a subject with PHT tendon injury based on isometric exercise, concentric/eccentric, energy storage, progressively increasing hip flexion was beneficial, increasing function and decreasing pain. Studies with a larger sample size and a more precise methodological design would be necessary to support this type of intervention in clinical practice. 5.

Characterization of Middle Cerebral Artery Velocity Kinetics in Response to Isometric Handgrip Exercise in Healthy Adults

Cerebral blood flow (CBF) is known to increase in response to both dynamic and isometric exercise. However, middle cerebral artery blood velocity (MCAv) kinetics in response to small-muscle isometric exercise, and sex differences in this kinetic response, require further investigation. Previous work suggests that MCAv response times to stressors may be indicative of cerebrovascular function, so the kinetics of this response to isometric exercise would add to the understanding of cerebrovascular health. The objective of this study was to characterize MCAv kinetics in response to isometric handgrip exercise and investigate potential sex differences in the response. We expected that MCAv at baseline would be higher in females than in males. However, we hypothesized that this sex difference would disappear during isometric handgrip exercise. In addition, we hypothesized that the time constant (τ) would be shorter in females compared with males, with a higher maximum response amplitude in females compared with males. Twenty-six healthy older adults with an average age of 56.8 ± 5.0 years (11 male (M) – aged 59.4 ± 4.8 years; 15 female (F) – aged 54.6 ± 4.1 years) completed an isometric handgrip exercise protocol. The exercise protocol consisted of the following: 1) performing a maximum voluntary contraction (MVC) with a handgrip device in the participants’ left hand (on a separate visit); 2) performing a sustained contraction until failure at 40% of the participant’s MVC. MCAv was continuously measured at rest and during handgrip exercise. The time constant was calculated as 63% of the time until steady-state MCAv during handgrip exercise. There was a trend for higher MCAv at baseline (57.8 ± 11.0 cm/s) in females (61.5 ± 11.2 cm/s) compared with males (53.6 ± 9.6 cm/s) that did not reach significance (p=0.08). There were no significant differences between the sexes for max amplitude of MCAv response to isometric handgrip exercise (M: 20.7 ± 11.1 cm/s; F: 15.4 ± 10.0 cm/s; p = 0.24) or time constant (M: 20.5 ± 9.8 sec; F: 18.6 ± 11.3 sec; p = 0.65). These results suggest no significant differences in MCAv between males and females at baseline. There also appear to be no significant sex differences in the kinetic response of MCAv to handgrip exercise. Future work could model MCAv kinetics in response to isometric handgrip exercise. The relationship between age and MCAv kinetics could also be investigated, along with the effect of menopause on MCAv kinetics in females. American Heart Association (19IPLOI34680015; JNB); American Heart Association COVID Supplement (19IPLOI34680015; JNB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Greater intramuscular metabolic perturbations contribute to faster muscle fatigue development in males than females during intermittent isometric exercise

INTRODUCTION: Previous studies reported faster performance fatigability in males than females during isometric exercise, ultimately prolonging time to task failure in the latter at the same relative intensity. Several authors suggested anatomical and physiological factors as primary determinants, but it remains unknown whether exercise-related accumulation of metabolites within skeletal muscle differentially affects fatigue development in female and males. PURPOSE: This study aimed to investigate intramuscular metabolic perturbations during fatiguing intermittent isometric knee-extensor exercise in males and females. Herein, we tested the hypothesis that greater metabolic perturbation during intermittent isometric exercise results in greater fatigue development in males compared to females. Methods: Fifteen males (M)(26±2y) and fifteen eumenorrheic females (F)(24±3y) visited the laboratory twice. During visit 1, isometric knee-extensors critical torque (CT) was estimated by a 5-min all-out test. In visit 2, participants performed intermittent isometric knee-extensor exercises to task failure at 110% of CT. To determine knee-extensors magnitude and etiology of fatigue maximal voluntary isometric contraction (MVIC), voluntary activation (VA) and potentiated twitches (St) amplitudes were evaluated before (PRE), at 9min (MID), and at task failure (POST). At the same time points, intramuscular pH and concentrations of ATP, PCr, Cr and La were determined in vastus lateralis muscle biopsies. Results: Time to task failure was shorter in M than F (1017±498 vs 1511±506s; P&lt;.01). At PRE, MVIC torque was higher in M than F (259±70 vs 152±24Nm; P&lt;.001). Relative decline in MVIC torque from PRE to MID was greater in M than F (-43±9 vs -34±8% from PRE; P&lt;.05) but reached similar decline at POST (-55±7 vs -53±6% from PRE). VA decreased throughout the test similarly in both sexes (P&lt;.001). St loss from PRE was higher in M than F (-45±13 vs -37±15%; P&lt;.05) at MID whereas no sex differences were observed at POST. Muscle pH decreased at a similar rate in M and F during the test (P&lt;.03). Muscle [ATP] did not change from PRE to MID or POST. Muscle [Cr] increased at a similar rate in M and F during the test (P&lt;.01). Muscle [PCr] was lower in M than F at any time point (P&lt;.03). At MID, [La] increased to a greater extent in M than F (P&lt;.01) with no between-sex differences at POST. CONCLUSION: Males showed greater fatigue development than females associated with greater metabolic perturbation during intermittent isometric exercise performed at same relative intensity. Higher PCr depletion and higher La accumulation suggest females were less fatigable than males due to higher glycolytic rate and less intramuscular inorganic phosphate concentration. The present work was funded by a Travelling Fellowship grant JEBTF2210859 to MC from The Company Of Biologists Limited. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

FEASIBILITY STUDY TO ASSESS THE DELIVERY OF A NOVEL ISOMETRIC EXERCISE INTERVENTION FOR PEOPLE WITH STAGE 1 HYPERTENSION

Objective: Adherence is low to the lifestyle changes recommended by NICE for patients with hypertension. More easily adopted, effective and manageable exercise interventions are needed. This study determined the feasibility of personalised isometric exercise (IE) for patients with Stage (grade) 1 hypertension in the National Health Service (NHS) in England. Design and method: We conducted a multicentre randomised controlled feasibility study delivered through NHS primary/secondary care. Patients included were 18+, with clinic systolic BP (SBP)140-159mmHg, not on anti-hypertensive medication and without significant medical contraindications. Participants were randomised to standard lifestyle advice (control) or standard lifestyle advice plus wall squat IE for a 6-month period (intervention). After excluding people with average home systolic &lt;135mmHg, 41 participants were included (control n=19, IE n=22) (aged 57 ± 15.15yrs). Participants were followed up at 4-weeks, 3-months, and 6-months. Results: Healthcare professionals were able to deliver the intervention with high fidelity (100% passed independent delivery check and 84.6% of participants recorded at least 2/3 of exercise heart rates within their target range over 6 months). A sample size for an efficacy trial (primary objective), was determined n= 542, based upon the 35% attrition rate and 14.4mmHg SD of change of SBP from baseline. Qualitative work provided valuable insights into acceptability, feasibility, delivery, and implementation in an NHS setting and for improved follow-on studies. Whilst the study was not powered to detect BP changes, reductions in SBP were observed at all time points. Figure 1. Marginal means and 95% CI from ANCOVA (Per-protocol population) Difference between means at each time point were: 4-weeks -2.31 mmHg (95% CI -11.29 to 6.67), 3 months -4.07 mmHg (95% CI, -10.28 to 2.15) 6 months -2.35 (95% CI -11.70-6.99). Pilot economic analyses suggested the intervention is cost-effective. Conclusions: Feasibility of IE has been demonstrated, but deliverability without significant modifications to the wall squat IE prescription protocol due to current NHS constraints would not be possible. Findings support investigating effectiveness of the intervention and justify a full RCT. A sample size of n=542 is needed to establish effectiveness.

Blood pressure responses to isometric handgrip exercise and post-exercise ischemia in females with no/low or high severity hot flash symptoms

Introduction: Severe menopausal hot flash symptoms are linked to the development of cardiovascular disease. Exaggerated blood pressure responses to exercise are also associated with an increased risk of hypertension and cardiovascular disease. It is unclear if females with more severe hot flash symptoms exhibit greater blood pressure responses to exercise compared to those with minimal menopausal hot flashes. We aimed to determine if there is a difference in the pressor response to isometric exercise between females with severe hot flash symptoms compared to females with no/low hot flash symptoms. We hypothesized that there will be exaggerated blood pressure responses to isometric handgrip exercise (IHG) and post-exercise ischemia (PEI) in females who have severe menopausal hot flashes compared to females with no/low hot flashes. Methods: We studied 19 female participants (age: 51±5yrs) with no history of cardiovascular disease or hypertension. The Menopausal Rating Scale (MRS) was used to assess the hot flash symptom severity and to group the participants into no/low (no-or-mild on MRS) or high (moderate-or-severe on MRS) hot flash symptom groups. Continuous blood pressure (BP) was measured via photoplethysmography and calibrated relative to a brachial arm cuff pressure. After 2 minutes of quiet rest, participants performed 2 minutes of IHG at 30% of maximal voluntary contraction, followed by 2 minutes of PEI on the exercising arm to isolate the metaboreflex. The severity groups were compared via independent samples t-tests. Results: There were 13 females in the no/low group and 6 females in the high group. Baseline heart rate (HR, no/low: 60±11 vs high: 58±8bpm), systolic (SBP, no/low:129±18 vs high: 120±14mmHg), diastolic (DBP, no/low: 72±12 vs high: 63±7mmHg) and mean BP (MBP, no/low: 91±11 vs high 82±9mmHg) were not different between groups. There were no differences in the pressor responses to IHG between groups (HR: no/low: Δ6±5 vs high: 5±4bpm, p=0.425; SBP: no/low: Δ9±5 vs high: 11±6mmHg, p=0.408; DBP: no/low: Δ5±3 vs high: 7±4mmHg, p=0.182; MBP: no/low: Δ6±3 vs high: 8±4mmHg, p=0.253). There was also no difference in the pressor response to PEI between groups (HR: no/low: Δ6±6 vs high: 4±2bpm, p=0.554; SBP: no/low: Δ11±6 vs high: 16±9mmHg, p=0.191; DBP: no/low: Δ5±3 vs high: 8±6mmHg, p=0.298; MBP: no/low: Δ7±4 vs high: 11±7mmHg, p=0.280). Conclusion: The current data show no differences in the blood pressure responses to IHG or PEI between females with different menopausal hot flash symptom severities. This suggests that pressor responses to an IHG exercise and the metaboreflex may not be notable contributors to the increased cardiovascular risk in females with severe menopausal hot flashes. NIH: K01 HL148144, NCATS UL1 TR000135, UL1 TR002377; AHA: 898649. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of Cytotoxic Chemotherapy and Endocrine Therapy on Hemodynamics and Oxygen Uptake During Handgrip Exercise in Patients Treated for Breast Cancer

Breast cancer therapies can alter skeletal muscle blood flow during exercise and decrease mitochondrial content and function. However, the impact of different therapies on the variables determining oxygen transport and utilization during submaximal exercise remain unknown. We tested the hypothesis that both chemotherapy and endocrine therapy would decrease blood flow and increase deoxygenated [hemoglobin+myoglobin] (HHb) with an unchanged oxygen uptake (VȮ2) during exercise compared to healthy controls. Participants were healthy females (CTRL; n = 5; age: 58 ± 8 years; body mass index: 25 ± 4 kg/m2) or female patients diagnosed with stage I-III breast cancer comprising three groups: 1) two to five weeks post completion of cytotoxic chemotherapy (CHEMO; n = 5; age: 55 ± 8 years; body mass index, BMI: 30 ± 4 kg/m2); 2) currently on endocrine therapy ≥5 months (ENDO; n = 9; age: 59 ± 7 years; BMI: 27 ± 6 kg/m2); and 3) completed cytotoxic chemotherapy and currently on endocrine therapy ≥5 months (CHEMO+ENDO; n = 8; age: 58 ± 6 years; BMI: 26 ± 5 kg/m2). Forearm blood flow, HHb, and estimated VȮ2 were measured during the final minute of a 3-minute intermittent isometric handgrip exercise at 3 and 6 kg. There were no group or group x intensity effects (all p&lt;0.18) for forearm blood flow (CTRL: 260 ± 33 ml/min; CHEMO: 407 ± 96 ml/min; ENDO: 309 ± 140 ml/min; CHEMO+ENDO: 313 ± 86 ml/min), HHb (CTRL: 134 ± 58 μM; CHEMO: 73 ± 36 μM; ENDO: 118 ± 67 μM; CHEMO+ENDO: 101 ± 25 μM), or estimated VȮ2 (CTRL: 59 ± 28 ml/min; CHEMO: 48 ± 21 ml/min; ENDO: 54 ± 28 ml/min; CHEMO+ENDO: 53 ± 21 ml/min). These findings indicate that chemotherapy and endocrine therapy do not affect muscle hemodynamics and oxidative metabolism during submaximal handgrip exercise. This study was funded, in part, by the Veterans Affairs Clinical Science Research and Career Development Award (IK2 CX002114). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effect of Acute Isometric Handgrip Exercise on Vascular Function in Children and Emerging Adults with Congenital Heart Disease

Endothelial dysfunction is common in congenital heart disease (CHD). Isometric handgrip (IHG) exercise may improve endothelial function; however, whether this applies to patients with CHD is unknown. We investigated brachial artery flow-mediated dilation (FMD) pre- and post- acute IHG exercise using duplex ultrasound in CHD and healthy controls (CTL; n=19 (7 F) vs. 21 (9 F), age: 13±4 vs. 13±4 y). Whereas IHG improved mean FMD in controls, it had no effect on the mean FMD response in patients with CHD. Subsequently, participants within each group were categorized based on ΔFMD response (post-pre IHG FMD), in which those that experienced a decrease were classified as non-responders (NRESP) and those that experienced an increase were classified as responders (RESP). Among NRESP, ΔFMD was lower in CHD vs. controls ( p=0.0224). Among RESP, ΔFMD was lower in CHD vs. controls ( p=0.0543). Data during pre-occlusion in NRESP from pre- to post-IHG exercise showed improved antegrade shear rate (condition effect, p=0.0078), retrograde shear rate (interaction effect, p=0.0410), and oscillatory shear index (interaction effect, p=0.049) in CHD compared to controls. Potentially, IHG exercise enhanced vascular sensitivity to shear, resulting in an increase in baseline diameter and reduced FMD in CHD NRESP. Thus, reduced FMD after acute IHG exercise is influenced by improvements in resting shear rate parameters in patients with CHD. Saskatchewan Health Research Foundation, Heart and Stroke Foundation of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Sex Differences in Left Ventricular Stroke Volume During Muscle Metaboreflex Activation

Introduction: Muscle metaboreflex activation (MMA) increases blood pressure, possibly by disproportionate increases in left ventricular (LV) stroke volume (SV) in males compared to females due to greater grip strength and metabolite production. The purpose of this study was to determine the effect of sex on SV during isolated MMA using cardiac MRI in young healthy adults. We hypothesized that SV would increase during MMA to a greater degree in males compared to females, and that this effect would be negated by accounting for grip strength. Methods: Ten males [23(2) yrs] and 10 females [26(5) yrs] underwent cardiac MRI during rest, 30% maximal voluntary contraction (MVC) isometric handgrip exercise (6 min), and isolation of MMA with brachial cuff circulatory occlusion (6 min). SV, end-systolic (ESV) and end-diastolic volumes (EDV) were measured by 2- and 4-chamber cine images and indexed (i) to body surface area to account for body size. Heart rate (HR, ECG) and mean arterial pressure (MAP, brachial cuff) were recorded. Cardiac output index (COi) and total peripheral resistance (TPR) were calculated. Analyses included ANOVA (sex × condition), ANCOVA [100% MVC (M=49(13) kg, F=26(7) kg) covariate], and linear regression. Results: SVi decreased from rest to MMA in males [67(8) to 61(5) mL/m2, p=0.0001] but not females [59(9) to 59(7) mL/m2, p=0.998; interaction p=0.002]. Notably, the reduction in SVi during MMA in males ( p=0.002) but not females ( p=0.957) remained with ANCOVA using MVC as the covariate (interaction p=0.021). ESVi increased during MMA in males [39(5) to 48(10) mL/m2, p&lt;0.0001] but not females [32(5) to 36(6) mL/m2, p=0.092; interaction p=0.029]. MMA decreased both EDVi ( p=0.004) and COi ( p=0.045) and increased both MAP ( p&lt;0.0001) and TPR ( p&lt;0.0001) pooled across sex. HR did not change with MMA in either sex (all p≥0.093). Linear regression revealed significant relationships between ΔSVi and ΔESVi in males ( p=0.002, R2=0.709) but not females ( p=0.223, R2=0.179) and between ΔSVi and ΔTPR in males ( p=0.005, R2=0.649) but not females ( p=0.522, R2=0.053). Conclusions: MMA lowers SVi in males but not females, even when accounting for grip strength and despite similar pressor responses in both groups. These findings from gold-standard MRI suggest differential LV responses to MMA between sexes, potentially related to greater sensitivity to increased TPR in males than females. Thus, sex differences in blood pressure control during MMA may be impacted by differences in LV afterload sensitivity. Further, the blood pressure response to MMA may be primarily mediated through TPR and not CO in healthy young adults. Heart and Stroke Foundation of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Blunted Exercise Pressor Reflex in Individuals with Down Syndrome

INTRODUCTION: Individuals with Down syndrome (DS) exhibit autonomic dysfunction, which contributes to reduced work capacity. The chemically sensitive component of the exercise pressor reflex, the metaboreflex, is responsible for exercise-induced sympathoexcitation and can be assessed via post-exercise muscle ischemia (PEMI). Blunted sympathoexcitation is common in individuals with DS and contributes to the physiological basis for reduced work capacity observed this population, but the influence of the metaboreflex is unknown. Using unilateral isometric knee extension exercise with PEMI, we hypothesized that individuals with DS would demonstrate a reduced metaboreflex compared to individuals without DS. METHODS: Twenty-four individuals with DS (M/F: 13/11; 24±5yrs; 30.3±6.2kg/m2) and without DS (M/F: 13/11; 25±4yrs; 26.5±4.5kg/m2) performed a unilateral isometric knee extension at 30% of their maximal voluntary contraction using their dominant leg on a leg dynamometer. Following 2-min of contraction, a thigh-cuff was rapidly inflated to 220 mmHg on the exercised leg for 3-min to isolate the activation of the muscle metaboreflex via PEMI. Beat-to-beat systolic blood pressure (SBP), stroke volume (SV), mean arterial pressure (MAP), and cardiac output (CO) were assessed using finger photoplethysmography coupled with Modelflow. Heart rate (HR) was collected via three-lead electrocardiogram. RESULTS: Despite similar baseline values of all variables in both groups, individuals with DS demonstrated a blunted pressor response to the isometric knee extension compared to individuals without DS (SBP; DS: 133±17 vs. Non-DS: 167±28 mmHg), and the blunted SBP response was maintained with PEMI (SBP; DS: 124±19 vs. Non-DS: 150±21 mmHg; time × group interaction, p&lt;0.001). Individuals with DS also exhibited a reduced HR 2-min into the contraction compared to those without DS (HR; DS: 90±16 vs. Non-DS: 114±22 bpm; timexgroup interaction, p&lt;0.001). Controlling for MVC, BMI, peak torque/body weight, and quadricep fat &amp; lean mass did not impact our results. Further, individuals with DS had a lower SV during the PEMI compared to individuals without DS (SV; DS: 93±24 vs. Non-DS: 113±23 mL/min; timexgroup interaction, p=0.003). CONCLUSION: Individuals with DS demonstrated a diminished metaboreflex response compared to their peers without DS, during a task known to induce sympathoexcitation, even when controlling for MVC. Our novel findings suggest that reduced influence of the metaboreflex contributes to the reduced exercise pressor response in persons with DS. Such exercise-specific peripheral autonomic perturbations contribute beyond our previous cardiac autonomic findings demonstrating blunted sympathoexcitatory perturbations in persons with DS, which likely contribute to reduced work capacity for this population. This research was funded in part by the American College of Sports Medicine Doctoral Research Award (#21-01558). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Potassium Supplementation Offsets the Effects of a High Sodium Diet on Endothelial Function but Not Blood Pressure Reactivity in Healthy, Normotensive Adults

High sodium diets are linked to endothelial dysfunction and increased blood pressure reactivity (BPR) to physiological stimuli, which are both notable cardiovascular disease (CVD) risk factors. High potassium diets are shown to lower blood pressure (BP) and improve endothelial function; however, previous interventions often increased potassium intake using food, making it diffcult to attribute these effects to potassium alone. The interactive effects of sodium and potassium on pre-clinical CVD risk factors remains unclear. The objective of this study was to determine if potassium can independently counteract the effects of a high sodium diet on endothelial function and BPR in healthy, normotensive adults. We hypothesized that endothelial function and BPR would be impaired with a high sodium diet compared to a low sodium diet but would improve with the addition of potassium supplements. Nineteen participants (13W/6M, age 26±4 y, BP 108±11/71±9 mmHg, BMI 25.1±2.7 kg/m2) completed three 10-day controlled diets in random order: a moderate potassium/low sodium (MK/LS; 55 mmol K/50 mmol Na) diet, a moderate potassium/high sodium (MK/HS; 55 mmol K/300 mmol Na) diet, and a high potassium/high sodium (HK/HS; 120 mmol K/300 mmol Na) diet. Potassium intake was increased using potassium chloride supplements. Dietary compliance was confirmed by urinalysis. On day 10, endothelial function was assessed by brachial artery flow-mediated dilation (FMD), and BPR was assessed by measuring ΔMAP in response to an isometric handgrip exercise (IHG) with post-exercise ischemia (PEI) and the cold pressor test (CPT). Differences across diets were assessed by repeated-measures ANOVA. Twenty-four-hour ambulatory mean arterial pressure (MAP), which was measured on day 9, was not different across diets (MK/LS: 81±5 mmHg; MK/HS: 79±4 mmHg; HK/HS: 80±6 mmHg; p=0.15), indicating our participants were salt-resistant. FMD was significantly lower on the MK/HS diet compared to the MK/LS diet (MK/HS: 5.8±2.8% vs. MK/LS: 8.2±3.7%; p=0.004) and was rescued with the addition of potassium supplements (HK/HS: 8.9±3.2; p=0.009 compared to MK/HS). FMD on MK/LS and HK/HS diets were similar (p&gt;0.05). There were no differences across diets in ΔMAP in response to the IHG (p=0.73), the PEI (p=0.67), or the CPT (p=0.94). Our findings suggest that, while sodium and potassium may not affect BPR, potassium supplementation effectively counteracts sodium-induced endothelial dysfunction in healthy, normotensive, salt-resistant adults. AHA/VIVA 23POST1009835; NHLBI R01 HL145055. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

347. Influence of Isometric Exercise on Circulating Endocannabinoid Concentrations in a Traumatic Injury Sample

347. Influence of Isometric Exercise on Circulating Endocannabinoid Concentrations in a Traumatic Injury Sample

Comparative analysis of two strength training protocols on throwing speed in women's handball

Shooting represents a fundamental skill in handball. Among other factors, its effectiveness requires a significant development of explosive strength. Isometric training may provide a powerful neuromuscular stimulus for its enhancement. Despite its importance and practicality, few studies have addressed the effect of this type of training on shooting speed in women's handball. Twenty female players were divided into two groups: isometric training (GI, n=10) and dynamic training (GD, n=10). Over nine weeks, twice a week, both groups completed an upper limb pushing resistance training: GI performed maximum isometric strength, and GD performed dynamic strength at 80% of one maximum repetition (1MR). In both cases, the effort was followed by medicine ball throws. The loads for both groups were equated in terms of sets and duration. Pre- and post-intervention, the 1MR of each player was estimated through a load progression test in bench press exercise. Additionally, the shooting speed with and without aiming at a target was measured from seven and nine meters using a radar. The findings showed a trend towards improvement in both groups (slightly higher in GI); however, only the not-targeted shooting speed from 9 meters in GI reached statistical significance (p &lt; .05). The correlation between 1MR and shooting speed was low to moderate. In summary, both types of training yielded similar results. Given the practical advantages of isometric training, it could be suggested that this training could serve as an effective and practical alternative for enhancing strength and shooting speed in handball. Keywords: Handball, handball shooting, isometric strength training, women's sport.

THE EFFECT OF ADMINISTERING TENS COMBINED WITH ISOMETRIC EXERCISES ON PAIN VALUES AMONG PATIENTS WITH KNEE OSTEOARTHRITIS AT THE IHC LAVALETTE HOSPITAL MALANG

Osteoarthritis causes changes within the digestion system of joint cartilage. These changes are within the shape of an increment within the action of chemicals that damage the macromolecules of the joint cartilage network, went with by a diminish within the blend of collagen and proteoglycans. This causes a decrease in proteoglycan levels, changes in the properties of collagen and reduced water content in joint cartilage causing pain in the knee. In this research, researchers used quantitative research methods or tested directly.The inquire about plan utilized by analysts is one bunch pretest-posttest plan. Within the One-Group Pretest-Posttest Plan the subordinate variable is measured as one bunch some time recently (pretest) and after (posttest) a treatment is given. The sample used in this study was 15 respondents who were given a combination of Transcutaneous Electrical Nerve Stimulation and isometric exercises. P value = 0.001 &lt; 0.05 Conclusion: H0 is rejected. H1 is accepted. There's a noteworthy impact of giving a combination of Transcutaneous Electrical Nerve Incitement and isometric works out on torment scores in patients with knee osteoarthritis at Lavalette Hospital, Malang.