Measures Of Aerobic Fitness Research Articles

The Effects of a 6-Week Plyometric and Sprint Interval Training Intervention on Soccer Player's Physical Performance.

Despite the well-documented benefits of sprint interval training (SIT) and plyometric training (PT) in improving the physical fitness of soccer players, it remains unclear which of these training methods is superior for enhancing players' aerobic and anaerobic performance. Therefore, this study aimed to compare the effects of SIT and PT on physical performance measures of male soccer players. Thirty male soccer players were randomly assigned to PT (n = 10), SIT (n = 10), and an active control group (CON, n = 10). Before and after the training period, participants underwent a battery of tests consisting of vertical jump, Wingate, linear sprint with and without ball dribbling, change of direction, ball kick, and the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) tests. Both groups exhibited similar improvements in maximal kicking distance (PT, effect size [ES] = 0.68; SIT, ES = 0.92) and measures of aerobic fitness including maximum oxygen uptake (PT, ES = 1.24; SIT, ES = 1.26) and first (PT, ES = 0.85; SIT, ES = 1.08) and second (PT, ES = 0.86; SIT, ES = 0.98) ventilatory thresholds. However, PT intervention resulted in greater changes in vertical jump (ES = 1.72 vs. 0.82, p = 0.001), anaerobic power (peak power, ES = 1.62 vs. 0.97, p = 0.009; mean power, ES = 1.15 vs. 1.20, p = 0.05), linear speed (20-m, ES = -1.58 vs. -0.98, p = 0.038; 20-m with ball, ES = -0.93 vs. 0.71, p = 0.038), and change of direction ability (ES = -2.56 vs. -2.71, p = 0.046) than SIT. In conclusion, both PT and SIT demonstrated effectiveness in enhancing aerobic performance among male soccer players. However, PT yielded superior improvements in anaerobic power, vertical jump, linear speed, and change of direction performance compared to SIT. These findings suggest that PT may offer additional benefits beyond aerobic conditioning.

Examining the impact of differing caffeine dosages in conjunction with plyometric training on physiological adaptations in basketball players

The aim of the current study was to investigate the effects of ingesting different dosages of caffeine (CAF) prior to plyometric jump training (PJT) on sport-related performance and physiological parameters in male basketball players. Twenty-four young athletes were randomly divided into 3 groups and performed 6 weeks of PJT while consuming 3 mg·kg–1 of body mass caffeine (CAF3, n = 8), 6 mg·kg–1 body mass caffeine (CAF6, n = 8) or placebo (PL; n = 8) one hour prior to each training session. Before and after the 6-week PJT, the players were evaluated for field-based basketball-specific performance measures (vertical jump, 20-m sprint, Illinois change of direction speed [CODS], and maximal strength) and lab-based physiological (aerobic capacity and anaerobic power) parameters. CAF3, CAF6, and PL groups demonstrated significant improvements in vertical jump (ES = 1.07, 1.45, and 1.1, respectively), 20-m sprint (ES = – 0.50, – 0.61, and – 0.36), change of direction performance (ES = – 1.22, – 1.26, and – 1.09), maximal strength (ES = 1.68, 2.29, and 1.17), maximum oxygen uptake (V̇O2max) (ES = 1.09, 1.59, and 0.92), and peak (ES = 1.82, 1.85, and 0.82) and average power output (ES = 1.39, 1.32, and 1.07) after 6 weeks of training. Comparative analysis of individual adaptive responses to training indicated that the CAF6 led to insignificantly greater effects in vertical jump (ES = 1.45), maximal strength (ES = 2.29), and V̇O2max (ES = 1.59) with lower residuals in individual changes and lower coefficient of variations (CV) in mean group changes. Regarding sprint and CODS performance, both experimental groups indicated similar changes, residuals in individual changes, and CVs in mean group changes. Overall, consuming 6 mg·kg–1 body mass caffeine induces superior adaptations in aerobic fitness, anaerobic power, and sport-specific performance measures, with lower inter-individual variability in the adaptations and more homogenized changes over the training period.

Optimal homeostatic stress to maximize the homogeneity of adaptations to interval interventions in soccer players.

This study examined the uniformity of adaptations in cardiorespiratory fitness and bio-motor abilities by analyzing individual responses to measures representing the mentioned qualities. Twenty-four male well-trained soccer players (Age = 26 ± 4years; stature = 181 ± 3.8; Weight = 84 ± 6.1) were randomized to two groups performing short sprint interval training [sSIT (3 sets of 10 × 4s all-out sprints with 20s of recovery between efforts and 3min of rest intervals between sets)] or a time-matched small-sided game [SSG (3 sets of 3 v 3 efforts in a 20 × 15m area with 3min of relief in-between)]. Before and after the 6-week training period, aerobic fitness indices, cardiac hemodynamics, and anaerobic power were assessed through a graded exercise test utilizing a gas collection system, noninvasive impedance cardiography, and a lower-body Wingate test, respectively. Also, sport-specific bio-motor abilities were determined by measuring linear speed, change of direction, and jumping ability. Comparing inter-individual variability in the adaptive changes by analyzing residuals in individual adaptations indicated that sSIT induces more uniform changes in the first and second ventilatory threshold (VT1 & VT2), stroke volume, and peak power output across team members than SSG. SSG also yielded lower proportions of responders in , VT1, VT2, peak, and average power output compared to sSIT. Additionally, the coefficient of variation in mean group changes in measures of aerobic fitness and bio-motor abilities in response to sSIT were lower than in SSG. Short sprint interval training induces more homogenized adaptations in measures of cardiorespiratory fitness and anaerobic power than small-sided games across team members.

Comparative Effects of Two High-Intensity Intermittent Training Programs on Sub-Elite Male Basketball Referees' Fitness Levels.

This study aimed to compare the effects of an 8-week short-term training program, comprising repeated sprints or running-based high-intensity intermittent training (HIIT), on the aerobic fitness and repeated sprint ability (RSA) performance of sub-elite basketball referees. Twenty male referees participated in supervised training sessions twice a week. They were randomly assigned to either the RSA-based group (RSAG) or the running-based HIIT group (HIITG). The RSAG conducted 3-4 sets of 8 × 20-m all-out sprints, while the HIITG performed 2-3 sets of 6 × 20-s runs at 90% of their maximal velocity achieved in the 30-15 intermittent fitness test (30-15IFT). Referees underwent a graded exercise test on a treadmill, the 30-15IFT, and an RSA test before and after the training program. Both groups showed significant improvement (~3%) in the fastest (22.6 ± 1.4 vs. 23.4 ± 1.7 and 22.0 ±1.9 vs. 22.4 ± 1.7 km·h-1 in RSAG and HIITG, respectively) and mean (21.5 ± 1.2 vs. 22.4 ± 1.4 and 21.3 ± 1.8 vs. 21.7 ± 1.6 km·h-1 in RSAG and HIITG, respectively) sprint velocity of the RSA test (p < 0.05). Moreover, positive changes (p < 0.05) were observed in the 30-15IFT maximal velocity (18.6 ± 1.1 vs. 19.3 ± 1.0 and 19.4 ± 0.9 vs. 20.5 ± 0.9 km·h-1 in RSAG and HIITG, respectively). In conclusion, an 8-week training intervention using either RSA or running-based HIIT led to similar improvements in referees' RSA performance and specific aerobic fitness measures. These findings could assist in devising tailored training programs for basketball referees.

The relationship between off-ice testing and on-ice performance in male youth Ice hockey players.

Ice hockey demands a unique blend of physical fitness and skill, necessitating a comprehensive understanding of the factors influencing on-ice performance. The present study was designed to examine the relationship between off-ice and on-ice performance measures in male, youth, ice hockey players. Eleven minor hockey players (Age = 9.8 ± 1.1 years) participated in two testing days: (1) off-ice and (2) on-ice assessments. Off-ice assessments included maximal aerobic power, anaerobic fitness, muscular strength (handgrip and single leg squat), muscular endurance (curl-ups and push-ups), muscular power (standing long jump and vertical jump), and 30 m sprinting speed and acceleration. On-ice testing included a 15.2 m maximum speed test, a 6.1 m acceleration test with a continuation into a 47.9 m top speed test, an agility cornering S turn test, and a shot velocity test. Twenty-four out of 33 off-ice variables were significantly correlated with at least one of the 11 on-ice performance variables. From those 24, 10 were included as predictors for at least one of the on-ice performance variables. Each model was composed of either one or two predictors, where the most common predictors were 30 m Run - Split (6.1 m) Sprint time and 30 m Run - Total (30 m) Sprint Max speed (included in four out of 11 models each). The prediction formulas R2 and coefficient of variation ranged from 0.63% to 0.96% and 1.2% to 15.3%, respectively. Diverse off-ice measures of aerobic fitness, anaerobic power, muscular strength, power, and endurance, and sprinting speed, acceleration, and agility are predictive of on-ice performance. The insights gained from this study contribute to the refinement of assessment protocols, fostering a comprehensive approach to optimizing player performance and potential. Understanding the connection between objective off-ice testing and on-ice performance can support tailored training programs and player development in male youth ice hockey.

Exercise Pathophysiology and Testing in Individuals With a Fontan Circulation.

The Fontan circulation, a surgical palliation for single-ventricle congenital heart disease, profoundly impacts the cardiopulmonary response to exercise. Reliant on passive pulmonary blood flow, the Fontan circulation has limited capacity to augment cardiac output as necessary to supply working muscles during exercise. Cardiopulmonary exercise testing (CPET) objectively assesses cardiorespiratory fitness and provides insight into the etiology of exercise intolerance. Furthermore, CPET variables, such as peak oxygen consumption and submaximal variables, have prognostic value and may be used as meaningful endpoints in research studies. CPET is also useful in clinical research applications to assess the effect of pharmacologic or other interventions. Medical therapies to improve exercise tolerance in individuals with a Fontan circulation, such as pulmonary vasodilators, may modestly improve peak oxygen consumption. Exercise training focused on aerobic fitness and lower extremity strength may have a more consistent and larger impact on these measures of aerobic fitness. CPET is a valuable diagnostic and prognostic tool for those with a Fontan circulation. Newer ancillary assessments, such as noninvasive peripheral venous pressure monitoring and cardiac output measurements, hold promise to provide a more nuanced insight into the underlying pathophysiology.

Reproducibility of NIRS-derived mitochondrial oxidative capacity in highly active older adults

IntroductionIn-vivo techniques using near-infrared spectroscopy (NIRS) have been developed to assess skeletal muscle mitochondrial oxidative capacity. However, the test-retest and day-to-day reliability of NIRS-derived mitochondrial oxidative capacity has yet to be established in older individuals. Therefore, the primary aim of this study was to determine the day-to-day and test-retest reliability of NIRS-derived mitochondrial oxidative capacity in older adults. The secondary aim was to examine the relationship between NIRS-derived mitochondrial capacity and whole-body aerobic fitness. Material and methodsTwenty-four healthy individuals (19 M, 5F; aged 60 ± 4 years; maximal oxygen uptake (V̇O2peak) = 41.2 ± 6.8 ml.kg−1.min−1) completed three visits to the laboratory. Visit one assessed isometric maximal voluntary contractions of the knee extensors and aerobic capacity through an incremental exercise test. In visits two and three participants completed two measurements of NIRS-derived mitochondrial oxidative capacity in the vastus lateralis (VL). ResultsNIRS-derived mitochondrial oxidative capacity was found to have good to excellent day-to-day reliability (Day 1 vs Day 2; coefficient of variation (CV) = 7.0 %; standard error of measurement (SEM) = 5.2; intra-class correlation coefficient (ICC) = 0.94) and test re-test reliability (Day 1 [Test 1 vs Test 2]; CV = 5.0 %; SEM = 3.7; ICC 0.97 and Day 2 [Test 1 vs Test 2]; CV = 6.3 %; SEM = 4.9; ICC = 0.93). NIRS-derived mitochondrial oxidative capacity was found to be significantly correlated with V̇O2peak (r = −0.61; R2 = 0.37; P = 0.002), oxygen uptake at the gas exchange threshold (r = −0.49; R2 = 0.24; P = 0.02), and oxygen uptake at the respiratory compensation point (r = −0.57; R2 = 0.32; P = 0.004). ConclusionNIRS provides a reliable method for deriving a measure of VL mitochondrial oxidative capacity in highly active older adults and demonstrates a significant relationship with measures of whole-body aerobic fitness.

Exercise Therapy in Early Multiple Sclerosis Improves Physical Function But Not Cognition: Secondary Analyses From a Randomized Controlled Trial

Background Exercise positively affects multiple sclerosis (MS) symptoms, physiological systems, and potentially cognition. However, an uninvestigated “window of opportunity” exists for exercise therapy early in the disease. Objective This study presents secondary analyses from the Early Multiple Sclerosis Exercise Study, and aims to investigate the efficacy of exercise on physical function, cognition, and patient-reported measures of disease and fatigue impact early in the disease course of MS. Methods This randomized controlled trial (n = 84, time since diagnosis <2 years) included 48 weeks of aerobic exercise or an active control condition (health education) and between-group changes are based on repeated measurement mixed regression models. Physical function tests included measures of aerobic fitness, walking (6-minute walk, Timed 25-foot walk, Six-spot step test), and upper-limb dexterity. Tests of processing speed and memory evaluated cognition. The questionnaires Multiple Sclerosis Impact Scale and Modified Fatigue Impact Scale assessed perception of disease and fatigue impact. Results Following early exercise aerobic fitness showed superior between-group physiological adaptations (4.0 [1.7; 6.3] ml O2/min/kg; large effect size [ES = 0.90]). No other outcomes showed significant between-group differences, yet all measures of walking and upper-limb function showed small-to-medium effect sizes in favor of exercise (ES = 0.19−0.58). Overall disability status as well as cognition were unaffected by exercise, whereas perception of disease and fatigue impact were reduced in both groups. Conclusion In early MS, 48 weeks of supervised aerobic exercise seem to positively modify physical function, but not cognitive function. Perception of disease and fatigue impact may be modifiable by exercise in early MS. Trial registration: Clinicaltrials.gov (identifier: NCT03322761).

Carbon monoxide monitoring to objectively measure smoking status in cardiac rehabilitation.

Participation in cardiac rehabilitation (CR) is associated with reduced morbidity and mortality. However, most programs rely on self-report measures when assessing the critical risk factor of smoking. This study examined smoking status using self-report versus objective measurement using expired carbon monoxide (CO) and compared patient characteristics by CO level. Patients were screened for smoking status when entering CR by self-report and by objectively measured CO. Measures of aerobic fitness, educational attainment, depressive symptoms, and self-reported physical function were also collected. The discrepancy between smoking status based on self-report and objective measurement was examined and patient characteristics by CO measurement were compared. Of the 853 patients screened, 62 self-reported current smoking and 112 had a CO of ≥ 4 ppm. Using a cut-off of ≥ 4 ppm encompassed almost all self-reported smokers (specificity: 98.5%) and identified 61 patients (not reporting current smoking) needing further screening. Further questioning yielded an additional 21 patients with combusted use (tobacco/cannabis), six nonsmoking patients with environmental CO exposure, and 34 where the reason for elevated CO was unknown. CO ≥ 4 ppm patients were younger (62.2 vs. 67.7, p < .01), had higher depression scores (5.6 vs. 3.7, Patient Health Questionairre-9, p < .01), had lower educational attainment (59.0% ≤ high school vs. 31.3%, p < .01), had lower levels of fitness (after controlling for clinical characteristics, p < .01), and completed fewer CR sessions (18 vs. 22, p < .01). A substantial number of patients who are actively smoking may be misclassified by relying on patient report alone. CO monitoring provides a simple and objective method of systematically screening patients. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Impact of Aerobic Exercise on Mood Symptoms in Trauma-Exposed Young Adults: A Pilot Study.

IntroductionPhysical activity has beneficial effects on mood in both healthy and clinical populations. Emerging literature suggests that physical activity may benefit psychological symptoms, such as depressive mood, in those with post-traumatic stress disorder (PTSD). It is estimated that 76% of Canadians have experienced a traumatic event during their lifetime (Van Ameringen et al., 2008). Thus, there is a large proportion of the population that does not meet criteria for PTSD but may still suffer from trauma-related symptoms such as depression and require support for their mental health. The current pilot study aimed to evaluate the impact of an aerobic exercise intervention on mood symptoms in trauma-exposed young adults.MethodsTwenty-five low active young adults with subclinical trauma symptoms but no current or past diagnosis of PTSD were recruited. Participants were randomly assigned to participate in an 8-week exercise intervention group or a waitlist control group. Mood symptoms were assessed before and after the intervention. In addition, measures of aerobic fitness, trauma symptoms, emotion regulation, and trait mindfulness were assessed at both time points.ResultsThe exercise intervention was effective at inducing the expected improvements in aerobic fitness. Overall, the exercise group had a significantly greater decrease in mood symptoms across the intervention compared to the waitlist control group.ConclusionThe current pilot study is the first to evaluate the impact of aerobic exercise on mood in trauma-exposed young adults. An 8-week intervention significantly reduced mood symptoms in exercisers relative to waitlist controls. Our results are consistent with previous research indicating that physical activity reduced depressive symptoms in those with PTSD (Rosenbaum et al., 2015b). Importantly, we extend these findings to individuals with subclinical or undiagnosed PTSD symptoms, where exercise may be an effective intervention to improve mood and manage or prevent further decline in mental health in those at risk of developing PTSD.

Changes in Australian law enforcement recruit aerobic fitness and the development of normative data after academy training

Background: Measures of aerobic fitness are an important component of law enforcement academy training to ensure a recruit’s physical capacity is sufficient to complete occupational demands. Law enforcement officers can be required to conduct rapid foot pursuits and restrain suspects, all while carrying additional loads (e.g., body armour and firearms). Thus, these officers require a sufficient level of fitness. Due to the importance of physical fitness in carrying out occupational tasks and reducing injury risk, this study aimed to quantify changes in aerobic fitness during law enforcement academy training and to establish normative aerobic fitness values which can evaluate recruit fitness across jurisdictions.

Associations between exercise, inflammation and symptom severity in those with mental health disorders

AimThis study aimed to investigate the effects of 6-weeks of moderate intensity aerobic exercise on markers of inflammation and symptom severity in those undergoing management of a mental health disorder. MethodTwenty six participants were allocated into two groups, those reporting as apparently healthy (AH, n = 13) or those undergoing the management of a mental health disorder (MI, n = 13). Following a baseline testing and familiarization session, participants commenced the 6-week aerobic training intervention, involving stationary cycling at 65% heart rate reserve for 35 min progressing to 70% for 40 min. Measures of aerobic fitness (VO2peak), anthropometric variables, symptom questionnaires and venous blood were collect pre- and post-intervention. Venous blood was assessed for nod-like receptor pyrin containing-3, interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), IL-1β, C-reactive protein (CRP) and brain-derived neurotropic factor (BDNF). ResultsThere were no baseline differences between groups, however following the intervention the AH demonstrated lower TNF-α (p = 0.049) than the MI group. Within change was observed for the MI group with an increase in VO2peak (p = 0.049) and declines in symptom severity (p = 0.00–0.005). Significant correlations between variables indicated a positive association between body fat, body fat percentage, CRP and symptom severity (p = 0.01–0.04). Conversely, symptom severity and CRP were inversely associated with VO2peak values (p = 0.02–0.04). ConclusionSix-weeks of moderate intensity aerobic exercise increases VO2peak and reduces symptom severity in those currently undergoing management of a mental health disorder. Further, there may be a physiological link between aerobic capacity, symptom severity, inflammation and adiposity, however greater exploration is required.

Relationship Between Movement Quality and Physical Performance in Elite Adolescent Australian Football Players.

Bennett, H, Fuller, J, Milanese, S, Jones, S, Moore, E, and Chalmers, S. The relationship between movement quality and physical performance in elite adolescent Australian football players. J Strength Cond Res 36(10): 2824-2829, 2022-The assessment of movement quality is commonplace in competitive sport to profile injury risk and guide exercise prescription. However, the relationship between movement quality scores and physical performance measures is unclear. Moreover, whether improvements in these measures are associated remain unknown. Over a 4-year period, 918 individual elite adolescent Australian Rules Footballers completed the Functional Movement Screen (FMS) and physical performance testing (5- and 20-m sprint, vertical jump, planned agility, and 20-m shuttle run test), allowing the analysis of relationships between FMS parameters and performance measures. In addition, 235 athletes completed testing over 2 consecutive years, allowing the analysis of relationships between changes in these outcomes. Small associations were observed between FMS composite score, hurdle step performance, in-line lunge performance, trunk stability push-up performance, rotary stability, and measures of speed, power, agility, and aerobic fitness (ρ = 0.071-0.238). Across consecutive seasons, significant improvements were observed in the deep squat subtest ( d = 0.21), FMS composite score ( d = 0.17), and 5- ( d = 0.16) and 20-m sprint times ( d = 0.39). A negative association between change in rotary stability and change in jump height (ρ = -0.236) from one season to the next was detected. Results suggest FMS scores have limited relationships with measures of performance in footballers. To optimize athletic performance, once acceptable movement capabilities have been established, training should not prioritize improving movement quality over improvements in strength, power, and change of direction ability.

Cross-sectional and prospective associations between aerobic fitness and lipoprotein particle profile in a cohort of Norwegian schoolchildren

Background and aimsThe associations between aerobic fitness and traditional measures of lipid metabolism in children are uncertain. We investigated whether higher levels of aerobic fitness benefit lipoprotein metabolism by exploring associations with a comprehensive lipoprotein particle profile. MethodsIn our prospective cohort study, we used targeted proton nuclear magnetic resonance (1H NMR) spectroscopy to profile 57 measures of lipoprotein metabolism from fasting serum samples of 858 fifth-grade Norwegian schoolchildren (49.0% girls; mean age 10.0 years). Aerobic fitness was measured using an intermittent shuttle run aerobic fitness test. We used multiple linear regression adjusted for potential confounders to examine cross-sectional and prospective associations between aerobic fitness and lipoprotein particle profile. ResultsHigher levels of aerobic fitness were associated with a favourable lipoprotein particle profile in the cross-sectional analysis, which included inverse associations with all measures of very low-density lipoprotein (VLDL) particles (e.g., −0.06 mmol·L−1 or –0.23 SD units; 95% CI = −0.31, −0.16 for VLDL cholesterol concentration). In the prospective analysis, the favourable pattern of associations persisted, though the individual associations tended to be more consistent with those of the cross-sectional analysis for the VLDL subclass measures compared to the low-density lipoproteins and high-density lipoproteins. Adjustment for adiposity attenuated the associations in both cross-sectional and prospective models. Nevertheless, an independent effect of aerobic fitness remained for some measures. ConclusionsImproving children's aerobic fitness levels should benefit lipoprotein metabolism, though a concomitant reduction in adiposity would likely potentiate this effect.

Is the metabolic power paradigm ecologically valid within elite Gaelic football?

To examine the association between the metabolic power paradigm during training and match-play and objective aerobic fitness measures within elite Gaelic football players. Twenty-five elite Gaelic football players completed objective physiological testing for VO2max, vVO2max, Peak treadmill Velocity (PTV), Running economy (RE) and selected blood lactate concentrations of 2 mmol L−1 (S2) and 4 mmol L−1 (S4). Aerobic testing was performed at the start of the season and at the halfway point of the season. Training and match-play running performances were recorded across the period with global positioning system technology (GPS; 4-Hz; VX Sport, Lower Hutt, New Zealand). Instantaneous raw velocity data were obtained from the GPS and exported to a customised spreadsheet which provided estimations of total distance (m), high-speed running distance (m; 17 km h−1), very-high-speed running distance (m; 22 km h−1), total accelerations (n), acceleration distance (m), peak and mean velocity (km h−1). Furthermore, changes in velocity were analysed which allowed for the assessment of the metabolic power paradigm during these training and match-play events. Players average metabolic power (Pmet; W Kg−1) observed to have a large association with VO2max (r = 0.76–0.88) and velocity at VO2max (r = 0.72–0.91) in training and match situations. Interestingly, peak treadmill velocity showed a moderate association with training and match-play high metabolic power distance (r = 0.56–0.76). Large associations were observed between high power distance during match and training categories and velocity at VO2max (r = 0.76–0.89). Furthermore, high power distance was observed to have a large association with peak treadmill velocity (r = 0.72–0.91) in training and match situations with lactate variables showing a small to moderate association with metabolic power variables. The current investigation is the first to provide evidence towards the ecological validity of the metabolic power paradigm to assess aerobic fitness within elite Gaelic football. Practitioners should consider the association between aerobic fitness and specific metabolic load paradigm variables within their monitoring system as a potential means to understand the impact of training plans within elite Gaelic football players.

Weekly vagal modulations and their associations with physical fitness and physical activity

The root mean square of successive differences (RMSSD) of R-R intervals, the most robust vagal modulation parameter of heart rate variability (HRV), has been proposed as a marker of global health and training adaptations. The weekly averaging of RMSSD and its natural logarithm (LnRMSSD) has been adopted to enhance detection of training-induced adaptations. We assessed measures of aerobic fitness, body composition, objective physical activity (PA), and daily LnRMSSD recordings during different conditions, such as supine rest, seated rest, standing and walking at 5 km/h, over a week in 34 healthy young individuals of both sexes (age: 22 ± 4 yr; body fatness: 20 ± 8%; estimated VO2max: 40 ± 8 mL·kg−1·min−1). The day-to-day reliability and agreement among LnRMSSD averages over 5, 4, 3, 2 and a single-day value per condition were assessed, while correlations between LnRMSSD, aerobic fitness, body composition, and PA were also examined. Poor to good day-to-day reliability, and moderate to excellent agreement were observed for LnRMSSD recordings for diverse conditions with a minimum of two daily recordings in the supine condition, and three in the other conditions achieving excellent agreement for weekly HRV assessment. Several correlations between LnRMSSD, aerobic fitness, body composition, and PA were revealed, with stronger observed associations during walking. Utilisation of weekly HRV (average of 2–3 daily recordings), as described in the current study, may provide practitioners with a tool to assess weekly vagal modulations for health and performance purposes. Walking HRV recordings may be a practical alternative to other conditions for the investigation of cardiac autonomic function.

The role of BMI on cognition following acute physical activity in preadolescent children.

There is an increasing prevalence of physical inactivity during childhood, concurrent with a rise in obesity rates, which is associated with a variety of health problems. However, the extent to which increased body mass index (BMI) influences acute physical activity (PA) benefits on cognition in childhood remains unknown. The aim of this study was to examine whether BMI influences the effects of acute PA on inhibitory control task performance. In a sample of 116 children pooled from four prior studies (ages 8-11; 51 females), demographic measures of age, sex, IQ, socioeconomic status, and aerobic fitness were considered along with BMI. Children participated in a counterbalanced, randomized crossover study, whereby they completed two different interventions; 20 minutes of treadmill walking (60-70% heart rate max) and restful reading (non-exercise control). Following each intervention, children performed a modified flanker task that manipulates inhibitory control demands. Correlations were conducted to determine the influence of demographic variables, fitness, and BMI on inhibitory control following each intervention. Subsequent hierarchical regression analyses were performed with significant demographic factors in the first step, aerobic fitness in the second step when significant, and BMI in the final step. Analyses indicated that children exhibited improved task performance (p's ≤ 0.001) and decreased interference (p=0.04) following the walking intervention compared to the restful reading control condition, indicating greater benefits following acute PA across task condition, with selectively greater benefits for the task condition requiring greater inhibitory control. Regression analyses revealed that greater BMI was related to decreased performance following acute PA (p=0.001); an association not observed following restful reading (p's ≥ 0.11). These results suggest that BMI negatively influences the effect of acute exercise on performance. Confirming previous studies, these findings indicate beneficial effects of acute PA on a flanker task that modulates inhibitory control requirements, but the effects are significantly greater for task conditions requiring greater amounts of inhibitory control. Further, these beneficial effects of PA appear to be blunted in children with higher BMI. These findings suggest that the acute benefits of PA on cognition may not be fully realized in children with higher BMI.

Developmental Trajectories of Body Mass Index, Waist Circumference, and Aerobic Fitness in Youth: Implications for Physical Activity Guideline Recommendations (CHAMPS Study-DK).

Describe the trajectories of body mass index (BMI), waist circumference, and aerobic fitness in children and identify different outcomes of guideline-recommended physical activity (PA) in a subset of active children. We recruited students from 10 public primary schools and obtained repeated measures of BMI, waist circumference, and aerobic fitness over 30months. Aerobic fitness was measured with the Andersen test. We objectively measured physical activity behaviour with accelerometers and classified children as 'physically active' when they achieved ≥ 60min of moderate-to-vigorous PA per day (guideline concordance). Univariate trajectories of BMI, waist circumference, and aerobic fitness were calculated for all children, and we constructed a multi-trajectory model comprising all outcomes in the subgroup of physically active children. The construct validity of all models was investigated by examining for between-group differences in cardiovascular disease risk factors obtained from fasting blood samples. Data from 1208 children (53% female) with a mean (SD) age of 8.4 (1.4) years were included. The univariate trajectory models identified three distinct trajectories for BMI, waist circumference, and aerobic fitness. The multi-trajectory model classified 9.1% of physically active children as following an 'overweight/obese/low fitness' trajectory. There were moderate-to-large differences in cardiovascular risk factors between all trajectory groups (p < 0.001; d = 0.4-1.20). We identified distinct developmental trajectories of BMI, waist circumference, and aerobic fitness in children. Nearly one in 10 children who met PA guideline recommendations followed an unfavourable health trajectory. Health-related PA recommendations may be insufficient for some children.

Investigating the influence of mtDNA and nuclear encoded mitochondrial variants on high intensity interval training outcomes

Mitochondria supply intracellular energy requirements during exercise. Specific mitochondrial haplogroups and mitochondrial genetic variants have been associated with athletic performance, and exercise responses. However, these associations were discovered using underpowered, candidate gene approaches, and consequently have not been replicated. Here, we used whole-mitochondrial genome sequencing, in conjunction with high-throughput genotyping arrays, to discover novel genetic variants associated with exercise responses in the Gene SMART (Skeletal Muscle Adaptive Response to Training) cohort (n = 62 completed). We performed a Principal Component Analysis of cohort aerobic fitness measures to build composite traits and test for variants associated with exercise outcomes. None of the mitochondrial genetic variants but eight nuclear encoded variants in seven separate genes were found to be associated with exercise responses (FDR < 0.05) (rs11061368: DIABLO, rs113400963: FAM185A, rs6062129 and rs6121949: MTG2, rs7231304: AFG3L2, rs2041840: NDUFAF7, rs7085433: TIMM23, rs1063271: SPTLC2). Additionally, we outline potential mechanisms by which these variants may be contributing to exercise phenotypes. Our data suggest novel nuclear-encoded SNPs and mitochondrial pathways associated with exercise response phenotypes. Future studies should focus on validating these variants across different cohorts and ethnicities.

Relationship Between Health-Related Quality Of Life, Aerobic Fitness, And Body Composition In Professional Firefighters

The firefighting profession requires high levels of physical fitness. Specifically, cardiovascular fitness has shown a strong relationship with the ability to perform occupational tasks. Despite this, not all firefighters maintain ideal fitness levels. Sudden cardiac arrest is the leading cause of on-duty fatalities for firefighters. Recent data suggests the prevalence of obese and overweight firefighters exceeds that of the general US population. Obesity is often correlated with low fitness levels in the general population, however when aerobic fitness improves, favorable outcomes in health related quality of life (HRQoL) have been reported. The relationship between HRQoL, aerobic fitness levels and body composition has not been studied in the professional firefighter population. PURPOSE: To determine the relationship of HRQoL, aerobic fitness, and body composition measures in professional firefighters. METHODS: 16 professional firefighters (14 male; 36±8 yrs; 178±10 cm; 87.0±20.0 kg; 27.1±3.7 kg/m2) completed baseline HRQoL survey, BodPod, and maximal oxygen uptake (VO2max) test. HRQoL was assessed using the SF-36, with the physical and mental composite scores used for analysis. Body fat percentage was estimated using BodPod. VO2max was assessed using a graded treadmill exercise test. Descriptive statistics (mean ± SD) were reported. Pearson correlation tests were used to assess association between variables. RESULTS: Overall participant anthropometrics are as follows: body fat (23.5 ± 6.8 %), VO2max (44.9 ± 6.0 mL/kg/min), physical health composite score (56.5 ± 2.6), and mental health composite score (48.9 ± 6.1). According to BMI classifications 6 firefighters were obese (>30 kg/m2) and 4 were overweight (25-29.9 kg/m2). There were statistically significant negative correlations between VO2max and body fat % (r = -0.88; p < 0.000), and fat mass (r = -0.86; p < 0.001). There was a positive correlation between physical health composite score and age (r = 0.57; p < 0.001). No other relationships were found to be statistically significant. CONCLUSIONS: The observed inverse relationship between aerobic fitness and body fat percentage supports prior findings. The novel finding that HRQoL was not correlated with aerobic fitness or body composition measures in this sample may warrant further study.