Submaximal Exercise Heart Rate Research Articles

Monitoring Within-Individual Dose-Response Relationships in Professional Soccer Players: The Importance of Fitness Level.

To (1)examine within-individual player dose-response associations between selected training-load measures and changes in aerobic fitness level via submaximal exercise heart rate (HRex%) and (2)measure the relationships between these dose-response associations with basal HRex% (to study the influence of fitness level on dose-response relationship). During an in-season phase, selected training-load measures including total minutes, total distance, mechanical work (the sum number of accelerations and decelerations > 3m2), high metabolic load distance, and Edwards' training impulse were collected via Global Positioning System and heart-rate sensors for analyzing accumulated load. A submaximal warm-up test was used repeatedly before and after 9 phases to elicit HRex% and track fitness changes at an individual level. Negative to positive extensive ranges of within-individual associations were found among players for different metrics (r = -.84 to .89). The relationship between pooled HRex% (basal fitness) and dose-response correlations showed inverse very large (r = -.71) and large (r = -.65) values for accumulated weekly minutes and distance. However, moderate values were found for all other measures (r = -.35 to -.42). Individual players show extensive different ranges of dose-response associations with training measures. The dose-response association is influenced by players' fitness level, and players with lower fitness levels show stronger inverse relationships with accumulated minutes and total distance.

The cardiovascular response to exercise in athletes recovering from SARS-CoV-2 infection: A prospective cohort study with repeated measures over 16 weeks – AWARE IX

ABSTRACT Higher exercise heart rate (HR) and prolonged return-to-sport in athletes with SARS-CoV-2 infection are described, but the cardiovascular response to exercise during recovery is not understood. This prospective, cohort, experimental study with repeated measures evaluated the cardiovascular response to exercise over 16 weeks in athletes recovering from SARS-CoV-2 infection. Athletes (n = 82) completed 2–5 repeat assessments at regulated intervals over 16 weeks post-SARS-CoV-2 infection. Data from 287 assessments (submaximal exercise tests; Modified Bruce protocol) are included. HR (bpm), systolic blood pressure (SBP) (mmHg) and rating of perceived exertion (RPE) (Borg scale 6–20) were measured. Rates of change in HR, SBP and RPE over time are reported. Submaximal exercise HR, SBP and RPE decreased significantly over 16 weeks (p < 0.01). There was a steeper rate of decline for HR and RPE ≤30 days compared to >30 days after SARS-CoV-2 infection: HR at Stage 3: ≤30 days −0.53 (0.01); >30 days −0.06 (0.02) and Stage 5: ≤30 days −0.77 (0.12); >30 days −0.12 (0.02); RPE at Stage 3: ≤30 days −0.09 (0.02); >30 days −0.01 (0.0002) and Stage 5: ≤30 days −0.13 (0.02); >30 days −0.02 (0.004). The findings provide clinical recommendation for exercise prescription and monitoring RPE in response to exercise post-SARS-CoV-2 infection and contribute to the clinical understanding of recovery which can help manage athlete expectations.

Assessing athlete readiness using physical, physiological, and perceptual markers

This systematic review and meta-analysis evaluated the validity of tests / markers of athletic readiness to predict physical performance in elite team and individual sport athletes. Ovid MEDLINE, Embase, Emcare, Scopus and SPORT Discus databases were searched from inception until 15 March 2023. Included articles examined physiological and psychological tests / markers of athletic readiness prior to a physical performance measure. 165 studies were included in the systematic review and 27 studies included in the meta-analysis. 20 markers / tests of athletic readiness were identified, of which five were meta-analysed. Countermovement jump (CMJ) jump height had a large correlation with improved 10m sprint speed / time (r = 0.69; p = .00), but not maximal velocity (r = 0.46; p = .57). Non-significant correlations were observed for peak power (r = 0.13; p = .87) and jump height (r = 0.70; p = .17) from squat jump, and 10m sprint speed / time. CMJ jump height (r = 0.38; p = .41) and salivary cortisol (r = -0.01; p = .99) did not correlate with total distance. Sub-maximal exercise heart rate (r = -0.65; p = .47) and heart rate variability (r = 0.66; p = .31) did not correlate with Yo-Yo Intermittent Recovery Test 1 performance. No correlation was observed between blood C-reactive protein and competition load (r = 0.33; p = .89). CMJ jump height can predict sprint and acceleration qualities in elite athletes. The validity of the other readiness tests / markers meta-analysed warrants further investigation.

Influence of age and gender on cardiovascular response to isometric exercise in apparently healthy individuals

Objective Static exercises are an integral aspect of patient rehabilitation and are employed in advanced strength and endurance training programmes. Exercise is a form of self-induced stress leading to circulatory and respiratory changes, therefore, this study sought to determine the influence of age and gender on the cardiovascular responses of apparently healthy individuals to isometric/static exercises. Methodology Sixty apparently healthy individuals (30 males and 30 females) participated in this study. Their ages ranged between 21–50 years and were grouped into 21–30 years, 31–40 years and 41–50 years. Each participant carried out and maintained 30% of maximal isometric voluntary contraction (MIVC) using hand grip for 1, 2 and 3 minutes respectively, with 30-minutes rest period. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured and recorded, at rest, and during each of the sustained contractions. Results There was a statistically significant increase (p &lt;0.05) in the mean SBP, DBP and HR at rest and with every increase in duration (that is, from 1 minute to 3 minutes) of static handgrip contraction, maintained at 30% MIVC in the 3 groups; except for HR for group one (that is, 21–30 years). There was no gender difference (p &gt;0.05) in SBP and DBP of the participants within the 3 groups, although male participants, particularly in group 2 had higher SBP. There was also a statistically significant increase in the HR of female participants compared to the males in group 2. Isometric contraction for 3 minutes produced the greatest change (increase) in cardiovascular parameter across all the groups but more marked among participants in group 2 (that is, 31–40 years). Conclusion The study concluded that submaximal (30% MIVC) isometric upper limb exercise increase blood pressure and heart rate in both sexes, with greatest values when the exercise was sustained for 3 minutes. Hence, efforts should be made to monitor cardiovascular parameters prior to prescribing safe level of isometric exercise. Also, 3 minutes of static/isometric exercises may be avoided, particularly during the rehabilitation of patient with cardiovascular disease.

Using Submaximal Exercise Heart Rate for Monitoring Cardiorespiratory Fitness Changes in Professional Soccer Players: A Replication Study.

To assess the value of monitoring changes in fitness in professional soccer players, using changes in heart rate at submaximal intensity (HR12km/h) over the velocity at a lactate concentration of 4mmol/L (v4mmol/L). The authors reexamined (1)a range of threshold magnitudes, which may improve detecting substantial individual changes and (2)the agreement between changes in these 2 variables. On at least 2 occasions during different moments of the season, 97 professional soccer players from Germany (first, second, and fourth division) completed an incremental test to determine HR12km/h and v4mmol/L. Optimal thresholds for changes in HR12km/h and v4mmol/L were assessed, using various methods (eg,smallest worthwhile change + typical error [TE], successive reiterations approach). Agreement between both variable changes was examined for the whole sample (225 comparisons), 4 different subgroups (depending on the moment of the season), and in an individual over 6 years (n = 23 tests). Changes of 4.5% and 6.0% for HR12km/h and v4mmol/L, respectively, were rated as optimal to indicate substantial changes in fitness. Depending on the (sub)groups analyzed, these thresholds yielded 0% to 2% full mismatches, 22% to 38% partial agreements, and 60% to 78% full agreements in terms of fitness change interpretation between both variables. When lactate sampling during incremental tests is not possible, practitioners willing to monitor adult professional soccer players' (Germany; first, second, and fourth division) training status can confidently implement short, 3-minute submaximal runs, with 4.5% changes in HR12km/h being indicative of true substantial fitness changes, with 60% to 78% accuracy. Future studies should investigate the potential role of confounding factors of HR12km/h to improve changes in fitness prediction.

Monitoring Cardiorespiratory Fitness in Professional Soccer Players: Is It Worth the Prick?

To compare between-tests changes in submaximal exercise heart rate (HRex, 3min, 12km/h) and the speed associated with 4mmol/L of blood lactate (V4mmol) in soccer players to get insight into their level of agreement and respective sensitivity to changes in players' fitness. A total of 19 elite professional players (23 [3]y) performed 2 to 3 graded incremental treadmill tests (3-min stages interspersed with 1min of passive recovery, starting speed 8km/h, increment 2km/h until exhaustion or 18km/h if exhaustion was not reached before) over 1.5 seasons. The correlation between the changes in HRex and V4mmol was examined. Individual changes in the 2 variables were compared (>2 × typical error considered "clear"). The changes in HRex and V4mmol were largely correlated (r = .82; 90% confidence interval, .65-.91). In more than 90% of the cases, when a clear individual change in HRex was observed, it was associated with a similar clear change in V4mmol (the same direction, improvement, or impairment of fitness) and conversely. When it comes to testing players submaximally, the present results suggest that practitioners can use HRex or V4mmol interchangeably with confidence. However, in comparison with a field-based standardized warm-up run (3-4min, all players together), the value of a multistage incremental test with repeated blood lactate samplings is questionable for a monitoring purpose given its time, labor, cost, and poorer player buy-in.

High Submaximal Exercise Heart Rate Impacts Exercise Intolerance in the Postural Orthostatic Tachycardia Syndrome.

Exercise intolerance is a hallmark of the postural orthostatic tachycardia syndrome (POTS). However, no data are available on the implications of an exaggerated submaximal heart rate (HR) on exercise intolerance in patients. We investigated whether exaggerated HR responses occurring early on during incremental stress testing relate with increased odds of POTS and exercise intolerance. Clinical characteristics and stress test HRs were compared between adults with POTS achieving ≥85% predicted metabolic equivalents (METs) (EX-TL, n = 101; body mass index [BMI] 24 ± 5 kg·m; 95% women) or <85% (EX-INTL, n = 71; BMI 28 ± 7 kg·m; 79% women) and sedentary controls (n = 30; BMI 36 ± 3 kg·m; 87% women). Multivariate logistic regressions were performed to estimate ORs and the probability of POTS and exercise intolerance associated with exercise HRs. Exercise tolerance was increased in EX-TL, but not in EX-INTL (10.0 ± 1.3 and 8.3 ± 1.5 METs vs 8.0 ± 1.6 METs, respectively) versus controls. Absolute peak HR was increased in EX-TL and EX-INTL versus controls (P < .01), whereas percent predicted did not differ. Exercise within the first-to-second stress stages was performed at exaggerated HRs (122 ± 17 bpm vs 103 ± 15 and 113 ± 15 bpm, P < .001) and percent HR reserve in EX-INTL versus controls and EX-TL (49% ± 12% vs 34% ± 11% and 41% ± 11%, P < .001), respectively. In multivariate analyses, peak HR was not significant, whereas increased submaximal HR (either variable) was associated with increased odds of EX-TL or EX-INTL. Lastly, odds of EX-INTL increased as METs decreased, whereas METs was not a predictor of EX-TL. An exaggerated submaximal exercise HR is predictive of POTS and exercise intolerance, and this chronotropic phenotype is exacerbated in patients achieving <85% predicted METs.

Safety and efficacy of omaveloxolone in patients with mitochondrial myopathy: MOTOR trial.

To investigate the safety and efficacy of escalating doses of the semi-synthetic triterpenoid omaveloxolone in patients with mitochondrial myopathy. In cohorts of 8-13, 53 participants were randomized double-blind to 12 weeks of treatment with omaveloxolone 5, 10, 20, 40, 80, or 160 mg, or placebo. Outcome measures were change in peak cycling exercise workload (primary), in 6-minute walk test (6MWT) distance (secondary), and in submaximal exercise heart rate and plasma lactate (exploratory). No differences in peak workload or 6MWT were observed at week 12 with omaveloxolone treatment vs placebo for all omaveloxolone dose groups. In contrast, omaveloxolone 160 mg reduced heart rate at week 12 by 12.0 ± 4.6 bpm (SE) during submaximal exercise vs placebo, p = 0.01, and by 8.7 ± 3.5 bpm (SE) vs baseline, p = 0.02. Similarly, blood lactate was 1.4 ± 0.7 mM (SE) lower vs placebo, p = 0.04, and 1.6 ± 0.5 mM (SE) lower vs baseline at week 12, p = 0.003, with omaveloxolone 160 mg treatment. Adverse events were generally mild and infrequent. Omaveloxolone 160 mg was well-tolerated, and did not lead to change in the primary outcome measure, but improved exploratory endpoints lowering heart rate and lactate production during submaximal exercise, consistent with improved mitochondrial function and submaximal exercise tolerance. Therefore, omaveloxolone potentially benefits patients with mitochondrial myopathy, which encourages further investigations of omaveloxolone in this patient group. NCT02255422. This study provides Class II evidence that, for patients with mitochondrial myopathy, omaveloxolone compared to placebo did not significantly change peak exercise workload.

Cardiac Parasympathetic and Anaerobic Performance Recovery After High-Intensity Exercise in Rowers.

To determine the effect of different high-intensity interval-training (IT) sessions on the postexercise recovery response and time course across varying recovery measures. A total of 13 highly trained rowers (10 male and 3 female, peak oxygen uptake during a 6-min maximal test 4.9 [0.7]L·min-1) completed 3 IT sessions on a rowing ergometer separated by 7 d. Sessions consisted of 5 × 3.5min, 4-min rest periods (maximal oxygen uptake [VO2max]); 10 × 30s, 5-min rest periods (glycolytic); and 5 × 10min, 4-min rest periods (threshold). Participants were instructed to perform intervals at the highest maintainable pace. Blood lactate and salivary cortisol were measured preexercise and postexercise. Resting heart-rate (HR) variability, post-submaximal-exercise HR variability, submaximal-exercise HR, HR recovery, and modified Wingate peak and mean power were measured preexercise and 1, 10, 24, 34, 48, 58, and 72 h postexercise. Participants resumed training throughout the measurement period. Between-groups short-term response differences (1 h post-IT) across IT sessions were trivial or unclear for all recovery variables. However, post-submaximal-exercise HR variability demonstrated the longest recovery time course (threshold = 37.8 [14.2], glycolytic = 20.2 [11.0], and VO2max = 20.6 [15.2]; mean [h] ± confidence limits). Short-term responses to threshold, glycolytic, and VO2max IT in highly trained male and female rowers were similar. Recovery time course was greatest following threshold compared with glycolytic and VO2max-focused training, suggesting a durational influence on recovery time course at HR intensities ≥80% HRmax. As such, this provides valuable information around the programming and sequencing of high-intensity IT for endurance athletes.

Interrelation between Exercise Heart Rate, Post-Run Systolic Blood Pressure, and Myocardial Structure in Distance Runners

Endurance running is an exercise practiced by athletes in many sports. Being benefi cial to health, it is also under-taken by a great number of non-athletic individuals. Rigorous endurance training frequently induces symmetric (i. e. both ventricular chamber dilation and wall thickening) myocardial hypertrophy, which is a physiological adapta-tion. Although distance running is a sport associated with haemodynamic volume rather than pressure overload, in addition to enlarged cardiac output, systolic arterial blood pressure also considerably increases during running. The extent of the cardiac hypertrophy was shown to be correlated with peak blood pressure measured during laboratory exercise. However, the predominant type of myocardial hypertrophy (the ratio between the myocardial wall thickness and chamber size) in endurance runners remains contradictory, and the majority of the responsible factors are still to be determined. The aim of this study was to determine possible correlations between post-run systolic blood pressure and myocardial hypertrophy in endurance runners.Standard transthoracic two-dimensional M-mode echocardiography was performed in white adult male distance runners (n = 49) of national level within four weeks of treadmill testing, which was a non-continuous incremental exercise test employed for the determination of the heart rate as well as post-exertional systolic blood pressure re-sponse. Runners’ training volume (evaluated as the average number of hours per week spent training averaged over the past four weeks) correlated (p &lt; 0.05) positively with the left ventricular (LV) wall thickness but not with the cavity size or LV mass (p &gt; 0.05). Training volume also positively correlated with systolic blood pressure response to exercise (p &lt; 0.05), but negatively with submaximal exercise heart rate (p &lt; 0.01). Post-run systolic blood pressure correlated positively with LV wall thickness and LV concentricity (namely, the ratio between the myocardial wall thick-ness and chamber size) (p &lt; 0.05), but no signifi cant correlation of any of the LV size parameters with resting heart rate, blood pressure, or systolic blood pressure in 2 to 4 min during the recovery period was revealed. Submaximal and maximal heart rate correlated signifi cantly and negatively with LV wall thickness, LV mass, and systolic blood pressure measured immediately after running (p &lt; 0.05).Training volume and post-run systolic blood pressure have been found to correlate positively with LV wall thickness and concentricity in white adult male distance runners. Negative correlation of exercise heart rate has been found with the post-exercise systolic blood pressure, LV wall thickness, and LV mass.Keywords: myocardial hypertrophy, pressure overload, echocardiography, athlete’s heart.

Semi-structured physical activity intervention in daily life: a good compromise between effectiveness and feasibility

As older-aged population is continuously increasing, it is essential to promote physical activity (PA) to preserve health and autonomy in daily living. Although several methods have been proposed, combining sustainability and efficacy at the same time is still a challenge. To evaluate the effects of a semi-structured PA (SSPA) intervention including aerobic as well as strength and flexibility exercise in comparison to generic PA advice (PAAdv) in healthy older adults. 86 sedentary older adults were divided in two groups, SSPA (n = 56) and PAAdv (n = 30). Body weight (BW) and circumferences, blood pressure (BP), submaximal exercise heart rate (HR), as well as Chair Stand Test (CST), Arm Curl Test (ACT), Chair Sit-and-Reach Test (CSRT) and Back Scratch Test (BST) were performed before and after 16 weeks of intervention. SSPA group was further divided in SSPA > 500 and SSPA 500 improved more than SSPA 500 and PAAdv groups. An SSPA program represents an ecological way to enhance fitness in older adults. A greater amount of SSPA (> 500 versus < 500 MET min/week) is associated with higher cardiovascular and muscular fitness benefits.

Aerobic interval training reduces vascular resistances during submaximal exercise in obese metabolic syndrome individuals.

The aim of this study was to determine the effects of high-intensity aerobic interval training (AIT) on exercise hemodynamics in metabolic syndrome (MetS) volunteers. Thirty-eight, MetS participants were randomly assigned to a training (TRAIN) or to a non-training control (CONT) group. TRAIN consisted of stationary interval cycling alternating bouts at 70-90% of maximal heart rate during 45minday-1 for 6months. CONT maintained baseline physical activity and no changes in cardiovascular function or MetS factors were detected. In contrast, TRAIN increased cardiorespiratory fitness (14% in VO2PEAK; 95% CI 9-18%) and improved metabolic syndrome (-42% in Z score; 95% CI 83-1%). After TRAIN, the workload that elicited a VO2 of 1500mlmin-1 increased 15% (95% CI 5-25%; P<0.001). After TRAIN when subjects pedaled at an identical submaximal rate of oxygen consumption, cardiac output increased by 8% (95% CI 4-11%; P<0.01) and stroke volume by 10% (95% CI, 6-14%; P<0.005) being above the CONT group values at that time point. TRAIN reduced submaximal exercise heart rate (109±15-106±13beatsmin-1; P<0.05), diastolic blood pressure (83±8-75±8mmHg; P<0.001) and systemic vascular resistances (P<0.01) below CONT values. Double product was reduced only after TRAIN (18.2±3.2-17.4±2.4btmin-1mmHg10-3; P<0.05). The data suggest that intense aerobic interval training improves hemodynamics during submaximal exercise in MetS patients. Specifically, it reduces diastolic blood pressure, systemic vascular resistances, and the double product. The reduction in double product, suggests decreased myocardial oxygen demands which could prevent the occurrence of adverse cardiovascular events during exercise in this population. CLINICALTRIALS. NCT03019796.

Women, Stress and Heart Health: Mindfulness-Based Stress Reduction and Cardiovascular Disease

Psychological stress including depression and anxiety are independent risk factors for cardiovascular disease morbidity and mortality, especially in women. Emotional regulation plays a mediating role in the development of depression and physical illness, and can alter resting physiologic responses associated with the stress response. Mindfulness-based stress reduction (MBSR) is a structured group program that employs mindfulness meditation to alleviate suffering associated with physical, psychosomatic, and psychiatric disorders. MBSR was originally developed for the management of chronic pain, which is now used widely to reduce psychological morbidity associated with chronic illnesses and to treat emotional and behavioral disorders. In cardiovascular disease, MBSR may be helpful for controlling several risk factors for coronary heart disease such as hypertension, type 2 diabetes mellitus, dyslipidemia, oxidative and psychosocial stress, obesity, and smoking, and improvements in submaximal exercise responses and heart rate variability. Although the most effective mode of stress reduction therapy is yet to be established, increasing recognition is being given to MBSR therapy.

Tracking Morning Fatigue Status Across In-Season Training Weeks in Elite Soccer Players.

To quantify the mean daily changes in training and match load and any parallel changes in indicators of morningmeasured fatigue across in-season training weeks in elite soccer players. After each training session and match (TL), session ratings of perceived exertion (s-RPE) were recorded to calculate overall session load (RPE-TL) in 29 English Premier League players from the same team. Morning ratings of fatigue, sleep quality, and delayed-onset muscle soreness (DOMS), as well as submaximal exercise heart rate (HRex), postexercise heart-rate recovery (HRR%), and heart-rate variability (HRV) were recorded before match day and 1, 2, and 4 d postmatch. Data were collected for a median duration of 3 wk (range 1-13) and reduced to a typical weekly cycle including no midweek match and a weekend match day. Data were analyzed using withinsubject linear mixed models. RPE-TL was approximately 600 arbitrary units (AU) (95% confidence interval 546-644) higher on match day than following day (P < .001). RPE-TL progressively decreased by »60 AU per day over the 3 days before a match (P < .05). Morning-measured fatigue, sleep quality, and DOMS tracked the changes in RPE-TL, being 35-40% worse on postmatch day vs prematch day (P < .001). Perceived fatigue, sleep quality, and DOMS improved by 17-26% from postmatch day to 3 d postmatch, with further smaller (7%-14%) improvements occurring between 4 d postmatch and prematch day (P < .01). There were no substantial or statistically significant changes in HRex, HRR%, or HRV over the weekly cycle (P > .05). Morning-measured ratings of fatigue, sleep quality, and DOMS are clearly more sensitive than HR-derived indices to the daily fluctuations in session load experienced by elite soccer players in a standard in-season week.

Submaximal Exercise Systolic Blood Pressure and Heart Rate at 20Years of Follow-up: Correlates in the Framingham Heart Study.

BackgroundBeyond their resting values, exercise responses in blood pressure (BP) and heart rate (HR) may add prognostic information for cardiovascular disease (CVD). In cross‐sectional studies, exercise BP and HR responses correlate with CVD risk factors; however, it is unclear which factors influence longitudinal changes in exercise responses over time, which is important for our understanding of the development of CVD.Methods and ResultsWe assessed BP and HR responses to low‐level exercise tests (6‐minute Bruce protocol) in 1231 Framingham Offspring participants (55% women) who underwent a routine treadmill test in 1979–1983 (baseline; mean age 39±8 years) that was repeated in 1998–2001 (follow‐up; mean age 58±8 years). Adjusting for baseline exercise responses, we related the follow‐up exercise responses to baseline CVD risk factors and to their changes between examinations. Compared with men, women had greater rise in exercise systolic (S)BP and HR at 20‐year follow‐up (both P<0.005). Baseline blood lipid levels, resting SBP and HR, and smoking status were associated with greater exercise SBP at follow‐up (all P<0.05). Weight gain across examinations was associated with higher exercise SBP and HR at follow‐up (both P<0.0001). Smoking cessation was associated with a 53% reduced risk of attaining the highest quartile of exercise SBP (≥180 mm Hg) at follow‐up (P<0.05).ConclusionAn adverse CVD risk factor profile in young adults and its worsening over time were associated with higher SBP and HR responses to low‐level exercise in midlife. Maintaining or adopting a healthy risk factor profile may favorably impact the exercise responses over time.

The effect of short-term intermittent hypoxic exposure on heart rate variability in a sedentary population.

While the effects of instantaneous, single-bout exposure to hypoxia have been well researched, little is known about the autonomic response during, or as an adaptation to, repeated intermittent hypoxic exposure (IHE) in a sedentary population. Resting heart rate variability (HRV) and exercise capacity was assessed in 16 participants (8 receiving IHE, [Hyp] and 8 receiving a placebo treatment [C]) before and after a 4-week IHE intervention. Heart rate variability was also measured during an IHE session in the last week of the intervention. Post-intervention, the root mean squared successive difference (rMSSD) increased substantially in Hyp (71.6 ± 52.5%, mean change ± 90% confidence limits) compared to C suggesting an increase in vagal outflow. However, aside from a likely decrease in submaximal exercise heart rate in the Hyp group (-5.0 ± 6.4%) there was little evidence of improved exercise capacity. During the week 4 IHE measurement, HRV decreased during the hypoxic exposure (reduced R-R interval: -7.5 ± 3.2%; and rMSSD: -24.7 ± 17.3%) suggesting a decrease in the relative contribution of vagal activity. In summary, while 4 weeks of IHE is unlikely to improve maximal exercise capacity, it may be a useful means of increasing HRV in people unable to exercise.

Heart rate response during underwater treadmill training in adults with incomplete spinal cord injury.

Walking on a submerged treadmill can improve mobility in persons displaying lower limb muscle weakness and balance deficits. Little is known, however, regarding the effect of water treadmill exercise on cardiac performance in persons with incomplete spinal cord injury (iSCI). To assess heart rate response during underwater treadmill training (UTT) in adults with iSCI. Seven males and 4 females with iSCI (age = 48 ± 13 years; 5 ± 8 years after injury) completed 8 weeks of UTT (3 sessions per week; 3 walks per session) incorporating individually determined walking speeds, personalized levels of body weight unloading, and gradual, alternating increases in speed and duration. Heart rate was monitored during the last 15 seconds of the final 2 minutes of each walk. Over the course of 3 biweekly periods in which walking speed remained constant, heart rate fell by 7% (7 ± 1 b•min(-1); P < .001) in weeks 2 and 3, 14% (17 ± 6 b•min(-1); P < .001) in weeks 4 and 5, and 17% (21 ± 11 b•min(-1); P < .001) in weeks 6 and 7. In adults with iSCI, progressively greater absolute and relative reductions in submaximal exercise heart rate occurred after 2 months of UTT featuring a systematic increase in training volume.

Effects of small-volume soccer and vibration training on body composition, aerobic fitness, and muscular PCr kinetics for inactive women aged 20–45

PurposeThe present study investigated the effects of 16 weeks of small-volume, small-sided soccer training soccer group (SG, n = 13) and oscillating whole-body vibration training vibration group (VG, n = 17) on body composition, aerobic fitness, and muscle PCr kinetics in healthy inactive premenopausal women in comparison with an inactive control group (CO, n = 14). MethodsTraining for SG and VG consisted of twice-weekly 15-min sessions with average heart rates (HRs) of ∼155 and 90 bpm respectively. Pre- and post-measurements of body composition (DXA), phosphocreatine (PCr) on- and off-kinetics, and HR measurements during standardised submaximal exercise were performed. ResultsAfter 16 weeks of training in SG, fat percentage was lowered (p = 0.03) by 1.7% ± 2.4% from 37.5% ± 6.9% to 35.8% ± 6.2% and the PCr decrease in the quadriceps during knee-extension ramp exercise was attenuated (4% ± 8%, p = 0.04), with no changes in VG or CO (time-group effect: p = 0.03 and p = 0.03). Submaximal exercise HR was also reduced in SG after 16 weeks of training (6% ± 5% of HRmax, p = 0.01). ConclusionShort duration soccer training for 16 weeks appears to be sufficient to induce favourable changes in body composition and indicators of aerobic fitness and muscle oxidative capacity in untrained premenopausal women.

Monitoring training status with HR measures: do all roads lead to Rome?

Measures of resting, exercise, and recovery heart rate are receiving increasing interest for monitoring fatigue, fitness and endurance performance responses, which has direct implications for adjusting training load (1) daily during specific training blocks and (2) throughout the competitive season. However, these measures are still not widely implemented to monitor athletes' responses to training load, probably because of apparent contradictory findings in the literature. In this review I contend that most of the contradictory findings are related to methodological inconsistencies and/or misinterpretation of the data rather than to limitations of heart rate measures to accurately inform on training status. I also provide evidence that measures derived from 5-min (almost daily) recordings of resting (indices capturing beat-to-beat changes in heart rate, reflecting cardiac parasympathetic activity) and submaximal exercise (30- to 60-s average) heart rate are likely the most useful monitoring tools. For appropriate interpretation at the individual level, changes in a given measure should be interpreted by taking into account the error of measurement and the smallest important change of the measure, as well as the training context (training phase, load, and intensity distribution). The decision to use a given measure should be based upon the level of information that is required by the athlete, the marker's sensitivity to changes in training status and the practical constrains required for the measurements. However, measures of heart rate cannot inform on all aspects of wellness, fatigue, and performance, so their use in combination with daily training logs, psychometric questionnaires and non-invasive, cost-effective performance tests such as a countermovement jump may offer a complete solution to monitor training status in athletes participating in aerobic-oriented sports.

Short-term high-intensity interval and continuous moderate-intensity training improve maximal aerobic power and diastolic filling during exercise

This study examined the effects of short-term high-intensity interval training (HIT) and continuous moderate-intensity training (CMT) on cardiac function in young, healthy men. Sixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six sessions over a 12-day training period. HIT consisted of 8-12 intervals of cycling for 60 s at 95-100% of pre-training maximal aerobic power (VO(2max)), interspersed by 75 s of cycling at 10% VO(2max). CMT involved 90-120 min of cycling at 65% pre-training VO(2max). Left ventricular (LV) function was determined at rest and during submaximal exercise (heart rate ~105 bpm) using two-dimensional and Doppler echocardiography. Training resulted in increased calculated plasma volume (PV) in both groups, accompanied by improved VO(2max) in HIT (HIT: from 39.5 ± 7.1 to 43.9 ± 5.5 mL kg(-1) min(-1); CMT: from 39.9 ± 5.9 to 41.7 ± 5.3 mL kg(-1) min(-1); P < 0.001). Resting LV function was not altered. However, increased exercise stroke volume (P = 0.02) and cardiac output (P = 0.02) were observed, secondary to increases in end-diastolic volume (P < 0.001). Numerous Doppler and speckle tracking indices of diastolic function were similarly enhanced during exercise in both training groups and were related to changes in PV. Short-term HIT and CMT elicit rapid improvements in VO2max and LV filling without global changes in cardiac performance at rest.