Bout Of Intermittent Exercise Research Articles

The Effects of Exercise on Synaptic Plasticity in Individuals With Mild Cognitive Impairment: Protocol for a Pilot Intervention Study.

Mild cognitive impairment (MCI) is a syndrome preceding more severe impairment characterized by dementia. MCI affects an estimated 15% to 20% of people older than 65 years. Nonpharmacological interventions including exercise are recommended as part of overall MCI management based on the positive effects of exercise on cognitive performance. Interval training involves brief intermittent bouts of exercise interspersed with short recovery periods. This type of exercise promotes cognitive improvement and can be performed in individuals with MCI. Synaptic plasticity can be assessed in vivo by the neurophysiological response to repetitive transcranial magnetic stimulation (rTMS). A method to assess synaptic plasticity uses an intermittent theta burst stimulation (iTBS), which is a patterned form of rTMS. Individuals with MCI have decreased responses to iTBS, reflecting reduced synaptic plasticity. It is unknown whether interval training causes changes in synaptic plasticity in individuals living with MCI. This research will determine whether interval training performed using a cycle ergometer enhances synaptic plasticity in individuals with MCI. The three aims are to (1) quantify synaptic plasticity after interval training performed at a self-determined intensity in individuals with MCI; (2) determine whether changes in synaptic plasticity correlate with changes in serum brain-derived neurotrophic factor, osteocalcin, and cognition; and (3) assess participant compliance to the exercise schedule. 24 individuals diagnosed with MCI will be recruited for assignment to 1 of the 2 equally sized groups: exercise and no exercise. The exercise group will perform exercise 3 times per week for 4 weeks. Synaptic plasticity will be measured before and following the 4-week intervention. At these time points, synaptic plasticity will be measured as the response to single-pulse TMS, reflected as the percent change in the average amplitude of 20 motor-evoked potentials before and after an iTBS rTMS protocol, which is used to induce synaptic plasticity. In addition, individuals will complete a battery of cognitive assessments and provide a blood sample from the antecubital vein to determine serum brain-derived neurotrophic factor and osteocalcin. The study began in September 2023. The proposed research is the first to assess whether synaptic plasticity is enhanced after exercise training in individuals with MCI. If exercise does indeed modify synaptic plasticity, this will create a new avenue by which we can study and manipulate neural plasticity in these individuals. ClinicalTrials.gov NCT05663918; https://clinicaltrials.gov/study/NCT05663918. PRR1-10.2196/50030.

A Perspective on High-Intensity Interval Training for Performance and Health

Interval training is a simple concept that refers to repeated bouts of relatively hard work interspersed with recovery periods of easier work or rest. The method has been used by high-level athletes for over a century to improve performance in endurance-type sports and events such as middle- and long-distance running. The concept of interval training to improve health, including in a rehabilitative context or when practiced by individuals who are relatively inactive or deconditioned, has also been advanced for decades. An important issue that affects the interpretation and application of interval training is the lack of standardized terminology. This particularly relates to the classification of intensity. There is no common definition of the term “high-intensity interval training” (HIIT) despite its widespread use. We contend that in a performance context, HIIT can be characterized as intermittent exercise bouts performed above the heavy-intensity domain. This categorization of HIIT is primarily encompassed by the severe-intensity domain. It is demarcated by indicators that principally include the critical power or critical speed, or other indices, including the second lactate threshold, maximal lactate steady state, or lactate turnpoint. In a health context, we contend that HIIT can be characterized as intermittent exercise bouts performed above moderate intensity. This categorization of HIIT is primarily encompassed by the classification of vigorous intensity. It is demarcated by various indicators related to perceived exertion, oxygen uptake, or heart rate as defined in authoritative public health and exercise prescription guidelines. A particularly intense variant of HIIT commonly termed “sprint interval training” can be distinguished as repeated bouts performed with near-maximal to “all out” effort. This characterization coincides with the highest intensity classification identified in training zone models or exercise prescription guidelines, including the extreme-intensity domain, anaerobic speed reserve, or near-maximal to maximal intensity classification. HIIT is considered an essential training component for the enhancement of athletic performance, but the optimal intensity distribution and specific HIIT prescription for endurance athletes is unclear. HIIT is also a viable method to improve cardiorespiratory fitness and other health-related indices in people who are insufficiently active, including those with cardiometabolic diseases. Research is needed to clarify responses to different HIIT strategies using robust study designs that employ best practices. We offer a perspective on the topic of HIIT for performance and health, including a conceptual framework that builds on the work of others and outlines how the method can be defined and operationalized within each context.

Acute effects of aerobic continuous, intermittent, and resistance exercise on glycemia in adolescents males with type 1 diabetes

Increased levels of physical activity is often associated with reduced HbA1c in individuals with diabetes. However, the effect on glycemic control differs between different programs of exercise. The aim of this study was to compare the acute effects on glycemia of resistance and two aerobic continuous and intermittent exercise bouts in adolescent males with type 1 diabetes. Eight active males with type 1 diabetes (17.5 ± 0.8 years, BMI: 20.8 ± 2.2 kg/m2 , HbA1c: 7.2 ± 0.5% [54.9 ± 5.3 mmol/mol]) performed four experimental sessions-nonexercise (control), resistance exercise (RE) and two isocaloric continuous (CE) and intermittent (IE) cycling exercise trials-in a randomized order. Each session consisted of 45 min of exercise (except for the control modality) and 60 min of passive recovery. Venous blood was drawn for assessment of plasma glucose (PG). A two-way repeated-measures ANOVA was used for statistical comparisons. A significant time-to-exercise interaction effect on PG was detected. PG significantly decreased during IE (-5.1 ± 1.6 mmol/L) and CE (-5.4 ± 1.8 mmol/L) but not during RE (-1.0 ± 1.4 mmol/L, ns). Additionally, decreases in PG after IE and CE were sustained throughout the recovery period. While intermittent and continuous aerobic exercises are associated with a lowering of glycemia in male adolescents with type 1 diabetes, glycemia remained stable without significant alterations after resistance exercise. These findings hold important implications related to clinical exercise advice and disease management in adolescents with type 1 diabetes.

Stepwise Load Reduction Training: A New Training Concept for Skeletal Muscle and Energy Systems.

An increased ability to supply energy to skeletal muscle is expected to contribute to greater athletic performance, and therefore, a variety of training methods are used for improving these energy supply systems. These methods are classified into two broad categories: a bout of continuous exercise at a given load/intensity and intermittent bouts of exercise at a given load/intensity with recovery intervals. Interestingly, recent work suggests that a training method which starts at a high load/intensity and gradually decreases the exercise load/intensity within a given training set (stepwise load reduction training) may provide a range of adaptations. In resistance training, the load starts off high and is then reduced as the set continues which is expected to simultaneously increase muscle strength, endurance, and size. In training focused on aerobic and anaerobic metabolic systems, intensity starts off high and is then reduced as the exercise continues which is expected to simultaneously increase maximal anaerobic power, anaerobic capacity, and aerobic capacity. Because stepwise load reduction training has no recovery intervals between each load/intensity, the training effects are achieved within a short time per session (several minutes). However, only minimal evidence exists to support the effects of stepwise load reduction training; therefore, further studies with larger samples are needed.

Walking Or Body Weight Squats May Improve Muscle Dietary Amino Acid Sensitivity During Prolonged Sitting

Low physical activity (e.g. reduced daily steps) reduces the ability of dietary amino acids (AA) to support muscle protein synthesis, leading to eventual muscle loss. Interrupting prolonged sitting with short bouts of intermittent exercise can improve carbohydrate and lipid metabolism, however its ability to sensitize skeletal muscle to dietary AA has yet to be investigated. PURPOSE: To determine the ability of interrupting prolonged sitting with practical ‘activity snacks’ to enhance the postprandial incorporation of dietary AA into myofibrillar protein. METHODS: As a subset of a larger study, twelve participants (7 males and 5 females; ~23y; ~40.0mlO2/kg/min; ~25.1kg/m2; ~4676 steps/d) completed three 7.5 hr trials in a randomized order consisting of prolonged sitting (SIT), sitting with intermittent walking (WLK; 2 min at 3.1mph every 30 min) or sitting with intermittent squatting (SQT; 15 ‘chair stands with calf raise’ every 30 min). Mixed-macronutrient meals (~55:30:15% carbohydrate:fat:protein) were provided at 20% (breakfast) and 30% (lunch) of daily energy requirements to be consistent with Western feeding patterns. Meals were enriched to 15% with ring-[2H5]phenylalanine or ring-[13C6]phenylalanine to model the metabolic fate of dietary AA. Muscle biopsies taken at the end of each trial as well as at the beginning of trial 2 were used to determine change in AA enrichment (LC/MS/MS) in the myofibrillar protein fraction (ΔMyo). RESULTS: ΔMyo was 0.032±0.004MPE in SIT and tended to be greater with SQT (0.038±0.003; P=0.10) and WLK (0.047±0.006; P=0.06) according to a prior comparisons (paired one-tail T-test). Relative to SIT, effect sizes were large for WLK (ES=0.88; 95% CI -0.30 - 2.07) and moderate for SQT (ES=0.55; 95% CI -0.60 - 1.71). CONCLUSION: Interrupting prolonged periods of sitting with intermittent bouts of body weight-dependent activity has the potential to improve the utilization of dietary AA for de novo muscle protein synthesis in young healthy adults. Our results add to the evidence that reducing sedentary time through ‘activity snacks’ may help maintain muscle mass and quality. Future research should determine whether at risk populations (e.g. aging, obese) may obtain a greater benefit from this simple lifestyle modification. Supported in part by an ACSM Research Endowment Grant.

Two days of calorie deprivation impairs high level cognitive processes, mood, and self-reported exertion during aerobic exercise: A randomized double-blind, placebo-controlled study

Military personnel and emergency responders perform cognitively-demanding tasks during periods of sustained physical exertion and limited caloric intake. Cognitive function is preserved during short-term caloric restriction, but it is unclear if preservation extends to combined caloric restriction and physical exertion. According to the “reticular-activating hypofrontality” model, vigorous exertion impairs prefrontal cortex activity and associated functions. This double-blind, placebo-controlled, crossover study examined cognitive function during sustained exertion while volunteers were calorically-deprived. Twenty-three volunteers were calorie-depleted for two days on one occasion and fully-fed on another. They completed intermittent bouts of exercise at 40–65% VO2peak while prefrontal cortex-dependent tasks of cognitive control, mood, and perceived exertion were assessed. Calorie deprivation impaired accuracy on the task-switching task of set-shifting (p < .01) and decreased sensitivity on the go/no-go task of response inhibition (p < .05). Calorie deprivation did not affect risk taking on the Rogers risk task. During exercise, calorie deprivation, particularly on day 2, increased perceived exertion (p < .05) and impaired mood states of tension, depression, anger, vigor, fatigue, and confusion (all p < .01). Physical exertion during severe calorie deprivation impairs cognitive control, mood, and self-rated exertion. Reallocation of cerebral metabolic resources from the prefrontal cortex to structures supporting movement may explain these deficits.

지속 혹은 분할 유산소 운동방법에 따른 에너지 소비량과 혈중 젖산 농도 비교

The aim of this study was to estimate and compare energy expenditure and blood lactic acid in a 30min continuous bout of bicycle ergometer cycling at 80% of HRmax reserve with 45 min of recovery and in 10 min intermittent bouts of exercise with equally divided into three 15min periods of recovery. Subjects were fourteen college-aged males(age: 22±1.8 years, height: 173±6.5 cm, weight: 70±13.8 kg, %body fat: 19±6.5%) volunteered to participate. Energy expenditure was measured with the POLOR(RS 800CX, Finland) & exercise record/analysis program and Lactate Tester (YSI 1500, USA), at warm up, exercise and during recovery. The 30 min continuous bouts of exercise included a 45 min recovery and each of the three 10 min bouts included 15 min of recovery. Workload was adjusted during exercise to maintain at 80% target HR. Setting of target HR was at 1/3 position of main exercise and maintaining to the end of the exercise. Differences in energy expenditure between continuous and intermittent exercise, recovery from exercise, as well as the combination of exercise an recovery were assessed with a paired t-test. And blood lactic acid concentration were analysis with independent t-test and oneway repeated measures ANOVA were employed to analyse blood lactatic acid. Significance was set a p<.05. The energy expenditure for exercise only was no significantly greater(6.3 kcal) with continuous bout of exercise than intermittent bouts of exercise. On the other hand, during recovery from exercise, they expended more energy(22.7 kcal) following intermittent exercise than following continuous exercise. The total energy expenditure for the combination of exercise and recovery was greater(16.3 kcal) than intermittent bouts of exercise, but it was not significant. And on blood lactic acid, there is significant different at point of exercise finish and at 15min of recovery(p<.01, p<.05 respectively).

Post-Exercise Blood Pressure and Autonomic Balance Following Continuous and Intermittent Exercise Bouts

Post-Exercise Blood Pressure and Autonomic Balance Following Continuous and Intermittent Exercise Bouts

Hybrid cooling vest for cooling between exercise bouts in the heat: Effects and practical considerations

While continuous cooling strategies may induce some ergonomic problems to occupational workers, cooling between work bouts may be an alternative for cooling them down in hot environments. The purpose of this study was to assess the effects of wearing a newly designed hybrid cooling vest (HCV) between two bouts of exercise. Inside a climatic chamber set at an air temperature of 37°C and a relative humidity of 60%, twelve male participants underwent two bouts of intermittent exercise interspersed with a 30min between-bout recovery session, during which HCV or a passive rest without any cooling (PAS) was administered. The results indicated that thermoregulatory, physiological, and perceptual strains were significantly lower in HCV than those in PAS during the recovery session (p≤0.022), which were accompanied with a large effect of cooling (Cohen's d=0.84–2.11). For the second exercise bout, the exercise time following HCV (22.13±12.27min) was significantly longer than that following PAS (11.04±3.40min, p=0.005, d=1.23) During this period, core temperature Tc was significantly lower by 0.14±0.0.15°C in HCV than that in PAS. The heart rate drift over time was declined by 2±2bpmmin−1 (p=0.001, d=1.00) and the rise in physiological strain index was reduced by 0.11±0.12unitmin−1 (p=0.010, d=0.96) following the use of HCV. These findings suggested that using HCV could accelerate between-bout recovery and improve subsequent exercise performance by the enlarged body core temperature margin and blunted cardiovascular drift.

The impact of intermittent exercise in a hypoxic environment on redox status and cardiac troponin release in the serum of well-trained marathon runners.

To investigate the effects of hypoxic training on redox status and cardiac troponin (cTn) release after intermittent exercise. Nine well-trained male marathon runners (age, 21.7±2.3year; body mass, 64.7±4.8kg; height, 177.9±3.8cm; and VO2max, 64.3±6.7mlkg(-1)min(-1)) completed intermittent exercise under normoxic [trial N; fraction of inspiration oxygen (FIO2), 21.0%] and hypoxic (trial H; FIO2, 14.4%) conditions in random order. Each bout of intermittent exercise included hard run (16.2±0.8kmh(-1)) at 90% VO2max for 2min followed by easy run (9.0±0.4kmh(-1)) at 50% VO2max for 2min and 23 bouts in 92min totally. Malondialdehyde, reduced glutathione (GSH), superoxide dismutase, an estimate of total antioxidant capacity (T-AOC), high-sensitivity cardiac troponin T (hs-cTnT), and cardiac troponin I (cTnI) were measured before, immediately after (0h), and 2, 4, and 24h after the completion of trials N and H. GSH was increased immediately after trial N. T-AOC was lower 4h after trial H than trial N. Hs-cTnT was elevated from 0 to 4h and returned to baseline 24h after both trials. CTnI was increased after trial H; peaked at 2-4h and returned to below the detection by 24h. The overall redox status was balanced under normoxic conditions, and exercise-induced cTn release did not deviate. However, the protective effects of antioxidant were weaker in the hypoxic state than normoxic, and the stress on the myocardium induced by intermittent exercise was transiently aggravated.

Differential Effects of 7 and 16 Groups of Muscle Relaxation Training Following Repeated Submaximal Intensity Exercise in Young Football Players.

This study compares two versions of progressive muscle relaxation (PMR) training (7 and 16 muscle groups) on oxygen consumption (VO2), heart rates, rating of perceived exertion and choice reaction time. Football (soccer) players (N = 26; M age = 13.4 yr., SD = 0.5) were randomly assigned to either 7 muscle groups PMR, 16 muscle groups PMR, or a control group. PMR training requires the participants to tense a muscle, hold the muscle contraction, and then relax it. Measurement was conducted prior to and after the completion of 12 sessions of PMR. The dependent variables were measured following four bouts of intermittent exercise consisting of 12 min. of running at 60% VO2max for 10 min. followed by running at 90% VO2max for 2 min. with a 3-min. rest for each bout. Lower VO2, heart rate, perceived exertion, and quicker reaction time were expected in both relaxation groups compared to the control group. The results revealed a significant reduction in heart rates and choice reaction time for both relaxation groups, but the longer version produced significantly quicker choice reaction time.

Aerobic Fitness and Trainability in Healthy Youth: Gaps in Our Knowledge

Peak oxygen uptake (VO2) is widely recognized as the criterion measure of young people's aerobic fitness. Peak VO2 in youth has been assessed and documented for over 75 years but the interpretation of peak VO2 and its trainability are still shrouded in controversy. Causal mechanisms and their modulation by chronological age, biological maturation and sex remain to be resolved. Furthermore, exercise of the intensity and duration required to determine peak VO2 is rarely experienced by most children and adolescents. In sport and in everyday life young people are characterized by intermittent bouts of exercise and rapid changes in exercise intensity. In this context it is the transient kinetics of pulmonary VO2 (pVO2), not peak VO2, which best describe aerobic fitness. There are few rigorously determined and appropriately analyzed data from young people's pVO2 kinetics responses to step changes in exercise intensity. Understanding of the trainability of pVO2 kinetics is principally founded on comparative studies of trained and untrained youth and much remains to be elucidated. This paper reviews peak VO2, pVO2 kinetics, and their trainability in youth. It summarizes "what we know," identifies significant gaps in our knowledge, raises relevant questions, and indicates avenues for future research.

Exercise-induced metabolic fluctuations influence AMPK, p38-MAPK and CaMKII phosphorylation in human skeletal muscle.

During transition from rest to exercise, metabolic reaction rates increase substantially to sustain intracellular ATP use. These metabolic demands activate several kinases that initiate signal transduction pathways which modulate transcriptional regulation of mitochondrial biogenesis. The purpose of this study was to determine whether metabolic fluctuations per se affect the signaling cascades known to regulate peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). On two separate occasions, nine men performed a continuous (30-min) and an intermittent exercise (30 × 1-min intervals separated by 1-min of recovery) at 70% of . Skeletal muscle biopsies from the vastus lateralis were taken at rest and at +0 h and +3 h after each exercise. Metabolic fluctuations that correspond to exercise-induced variation in metabolic rates were determined by analysis of VO2 responses. During intermittent exercise metabolic fluctuations were 2.8-fold higher despite identical total work done to continuous exercise (317 ± 41 vs. 312 ± 56 kJ after intermittent and continuous exercise, respectively). Increased phosphorylation of AMP-activated protein kinase (AMPK) (˜2.9-fold, P < 0.01), calcium/calmodulin-dependent protein kinase II (CaMKII) (˜2.7-fold, P < 0.01) and p38-mitogen-activated protein kinase (MAPK) (˜4.2-fold, P < 0.01) occurred immediately in both exercises and to a greater extent after the intermittent exercise (condition x time interaction, P < 0.05). A single bout of intermittent exercise induces a greater activation of these signaling pathways regulating PGC-1α when compared to a single bout of continuous exercise of matched work and intensity. Chronic adaptations to exercise on mitochondria biogenesis are yet to be investigated.

Impact of Acute Intermittent Exercise on Natural Killer Cells in Breast Cancer Survivors.

Current research examining the effect of exercise on immune responses in cancer survivors is limited. The aim of this pilot study was to examine the effect of 1 bout of intermittent exercise on natural killer (NK) cell numbers in breast cancer survivors. A total of 9 women with stage I to III invasive breast cancer who were 3 to 6 months posttreatment and 9 sedentary women without a history of cancer completed 10 three-minute intervals of aerobic exercise on the cycle ergometer at 60% of VO2peak (peak oxygen uptake). Whole blood samples were taken pre-exercise, immediately postexercise, and at 2 hours and 24 hours postexercise. NK cell counts were assessed using flow cytometry. In both groups, NK cell counts significantly increased immediately postexercise compared with pre-exercise (P = .004-.008) and returned to near pre-exercise levels during recovery (P = .129-.547). Absolute NK cell counts were significantly lower in breast cancer survivors immediately postexercise when compared with controls (P = .046). The breast cancer survivor group exhibited NK cell responses to 30 minutes of moderate-intensity intermittent aerobic exercise that were comparable with that in the group of physically similar women without a history of cancer. Immune changes related to cancer treatments may be related to the lower absolute NK cell counts observed in the breast cancer survivor group. Although the results of this study are preliminary in nature, they suggest that this type of exercise does not disrupt this aspect of innate immunity in recent breast cancer survivors, thereby supporting current exercise recommendations for this population.

Evidence for cyclooxygenase-dependent sweating in young males during intermittent exercise in the heat.

Key points Previous studies implicate nitric oxide (NO) in the control of sweating during exercise in the heat; however, it is unclear whether cyclooxygenase (COX) is also involved. We demonstrated that exercise‐induced sweating at a moderate heat production (400 W, ∼40% was similarly reduced when COX and NO synthase were inhibited separately and in combination. Alternatively, inhibiting COX and/or NO synthase did not influence exercise‐induced sweating at a high heat production (700 W, ∼70% We show that both COX and NO are involved in sweating during exercise at moderate heat production and that the effects may not be independent. However, roles for COX and NO are less evident when heat production is elevated. The results lead to better understanding of the mechanisms of sweating and indicate that COX inhibitors (e.g. aspirin) may impair core body temperature regulation and thereby increase the risk of heat‐related illness. AbstractOur recent work implicated nitric oxide (NO) in the control of sweating during intermittent exercise; however, it is unclear if cyclooxygenase (COX) is also involved. On separate days, ten healthy young (24 ± 4 years) males cycled in the heat (35°C). Two 30 min exercise bouts were performed at either a moderate (400 W, moderate heat load) or high (700 W, high heat load) rate of metabolic heat production and were followed by 20 and 40 min of recovery, respectively. Forearm sweating (ventilated capsule) was evaluated at four skin sites that were continuously perfused via intradermal microdialysis with: (1) lactated Ringer solution (Control), (2) 10 mm ketorolac (a non‐selective COX inhibitor), (3) 10 mm NG‐nitro‐l‐arginine methyl ester (l‐NAME; a non‐selective NO synthase inhibitor) or (4) a combination of 10 mm ketorolac + 10 mm l‐NAME. During the last 5 min of the first exercise at moderate heat load, forearm sweating (mg min−1 cm−2) was equivalently reduced with ketorolac (0.54 ± 0.08), l‐NAME (0.55 ± 0.07) and ketorolac+l‐NAME (0.56 ± 0.08) compared to Control (0.67 ± 0.06) (all P &lt; 0.05). Similar results were obtained for the second exercise at moderate heat load (all P &lt; 0.05). However, forearm sweating was similar between the four sites during exercise at high heat load and during recovery regardless of exercise intensity (all P &gt; 0.05). We show that (1) although both COX and NO modulate forearm sweating during intermittent exercise bouts in the heat at a moderate heat load, the effects are not additive, and (2) the contribution of both enzymes to forearm sweating is less evident during intermittent exercise when the heat load is high and during recovery.

Whole body heat loss is reduced in older males during short bouts of intermittent exercise

Studies in young adults show that a greater proportion of heat is gained shortly following the start of exercise and that temporal changes in whole body heat loss during intermittent exercise have a pronounced effect on body heat storage. The consequences of short-duration intermittent exercise on heat storage with aging are unclear. We compared evaporative heat loss (HE) and changes in body heat content (ΔHb) between young (20-30 yr), middle-aged (40-45 yr), and older males (60-70 yr) of similar body mass and surface area, during successive exercise (4 × 15 min) and recovery periods (4 × 15 min) at a fixed rate of heat production (400 W) and under fixed environmental conditions (35 °C/20% relative humidity). HE was lower in older males vs. young males during each exercise (Ex1: 283 ± 10 vs. 332 ± 11 kJ, Ex2: 334 ± 10 vs. 379 ± 5 kJ, Ex3: 347 ± 11 vs. 392 ± 5 kJ, and Ex4: 347 ± 10 vs. 387 ± 5 kJ, all P < 0.02), whereas HE in middle-aged males was intermediate to that measured in young and older adults (Ex1: 314 ± 13, Ex2: 355 ± 13, Ex3: 371 ± 13, and Ex4: 365 ± 8 kJ). HE was not significantly different between groups during the recovery periods. The net effect over 2 h was a greater ΔHb in older (267 ± 33 kJ; P = 0.016) and middle-aged adults (245 ± 16 kJ; P = 0.073) relative to younger counterparts (164 ± 20 kJ). As a result of a reduced capacity to dissipate heat during exercise, which was not compensated by a sufficiently greater rate of heat loss during recovery, both older and middle-aged males had a progressively greater rate of heat storage compared with young males over 2 h of intermittent exercise.

Upper body exercise increases lower extremity venous blood flow in deep venous thrombosis.

Sequential compression devices or ambulation prevent deep venous thrombosis (DVT) by enhancing venous blood flow in the lower extremity. However, compression therapy or ambulation may not be possible in patients with lower extremity surgery or trauma. We therefore determined whether upper body exercise increases venous blood flow in the lower extremities as a potential means for preventing DVT. We determined blood volume flow and velocity responses in the common femoral veins to low-intensity (5 W, 75 rpm) upper body cycle ergometry in healthy individuals. Six protocols of single and intermittent bouts of exercise were tested. Upon determination of the most efficacious protocol in these participants, we verified the effects of upper body exercise in patients with acute DVT. Measurements were made before, during, and after exercise using duplex ultrasound imaging. The study enrolled 15 healthy volunteers (10 men, 5women; aged 20-40 years) with no history of DVT and 10patients (aged 31-86 years) with acute DVT. In healthy participants, a single 30-second bout of upper body exercise increased volume flow up to 39% for up to 10 minutes after exercise (P< .05). A single 3-minute bout increased flow to a lesser extent (23% increase; P= .05) for nearly 5 minutes, but a single 1-minute bout did not increase flow. An intermittent protocol of three 30-second bouts of exercise resulted in an increase of 34% to 57% in venous flow (P< .05) for an average increase of 179± 53 mL/min. Intermittent 1-minute bouts of exercise tended to increase flow 10% to 40% (P= .06-.08) for an average increase of 149± 64 mL/min. Intermittent 3-minute bouts of exercise increased flow 21% to 45% (P< .05) for an average increase of 120± 42 mL/min. In patients with acute DVT, the intermittent 30-second upper body exercise protocol increased venous blood flow by 45% to 83% (P< .05) for an average increase of 250± 63 mL/min, an effect lasting >13 minutes. We report the novel finding that upper body exercise increases lower extremity venous blood flow in healthy volunteers and in acute DVT patients. Three intermittent 30-second bouts of low-intensity upper body exercise elicited the highest response for the least amount of effort and may represent an alternative or adjunct for prophylaxis of DVT in patients with restricted ambulation.

Intermittent exercise in response to cigarette cravings in the context of an Internet-based smoking cessation program

BackgroundInterventions using sustained aerobic exercise programs to aid smoking cessation have resulted in modest, short-term cessation rates comparable to conventional cessation methods. No smoking cessation trial to date has prescribed intermittent bouts of exercise in response to nicotine cravings. ObjectivesThis pilot randomized controlled trial examined the feasibility and efficacy of an Internet-based smoking cessation program alone (CON) vs. the same Internet-based program + intermittent exercise in response to cigarette cravings (EX). Study populationParticipants (N = 38; mean age = 43.6 [SD = 11.5]; 60.5% women) were generally healthy, inactive adult smokers who desired to quit. ResultsThe overall retention rate was 60.5% (n = 23), and no significant retention rate differences were found between groups (EX vs. CON). Although retained participants achieved a higher cessation rate (26.1%) than all enrolled participants (15.8%), adjusted intent-to-treat and per-protocol binary logistic regression analyses revealed no significant cessation rate differences between EX and CON groups. Linear regression results indicated that additional days of self-reported exercise on the study website during the intervention phase predicted significantly higher reduction rates among EX group participants, F(2, 16) = 31.08, p < .001. ConclusionsResults were mixed with regard to the incremental benefit of exercise in the presence of the apparently valuable Internet-based smoking cessation program. The results support findings from related research and underscore the need for additional investigation into both the mechanisms underlying the effect of exercise on cigarette cravings and the challenges of poor adherence in the context of exercise-based smoking cessation interventions.

N-Acetylcysteine’s Attenuation of Fatigue After Repeated Bouts of Intermittent Exercise: Practical Implications for Tournament Situations

Production of reactive oxygen species (ROS) during muscle contractions is associated with muscle fatigue and damage in the short term and adaptive responses in the long term. When adaptation is inconsequential acute antioxidant supplementation may be able to attenuate muscle fatigue and damage to enhance performance. This study aimed to determine the effects of acute oral N-acetylcysteine (NAC) supplementation on Yo-Yo Intermittent Recovery Test Level 1 (YIRT-L1) performance after repeated bouts of damaging intermittent exercise. In a pair-matched design, 12 recreationally trained men engaged in 6 d of either NAC (n = 6) or placebo (n = 6) supplementation. After a treatment-loading day, participants completed 3 testing sessions, on alternating days, consisting of a preexercise isokinetic dynamometry (IKD) test, a damaging intermittent-exercise protocol, YIRT-L1, and a postexercise IKD test. Another IKD test was completed on the 2 intervening d. NAC treatment resulted in a significant preservation of YIRT-L1 performance (p ≤ .0005). IKD performance significantly deteriorated over time at all contraction speeds, and this deterioration was not influenced by treatment group. Plasma creatine kinase values increased significantly over time (p = .002) and were significantly greater in the NAC group than in the placebo group (p = .029). NAC induced mild gastrointestinal side effects. NAC supplementation may be a useful strategy to enhance performance during short-term competitive situations when adaption is inconsequential. Titration studies to elucidate a treatment dose that enhances performance without inducing side effects are now required.

Postural Stability in Adolescent Boys During Repeated Bouts of Intermittent Exercise in the Heat

Postural Stability in Adolescent Boys During Repeated Bouts of Intermittent Exercise in the Heat