The prescription of aerobic exercise modalities engaging the arm musculature have the potential to extend the reach of physical activity and promote cardiorespiratory fitness in individuals with lower body impairment due to excessive body mass, and among individuals seeking to complement and diversify standard leg training. This study compared the acute cardiopulmonary responses obtained during arm cycling and leg cycling performed at different intensities among lean and average (LA) and overfat and obese individuals (OFO). Participants were 37 young and relatively healthy adults. They were tested for mode-specific peak power output and work rate at ventilatory threshold during two randomized maximal incremental protocol tests. The experiments were four randomized constant work rate isocaloric protocols for arm cycling and leg cycling performed at heavy and moderate exercise intensities based on participants' ventilatory threshold and peak power output obtained from the maximal incremental protocol tests. All experiments were matched for the same caloric expenditure of 100 kcal. Cardiopulmonary parameters and the time to expend 100 kcal (Tkcal100) were recorded. Tkcal100 was increased for the OFO in comparison to the LA group. Among the cardiopulmonary parameters measured in this study, only oxygen uptake relative to body mass was significantly different between groups; however, differences were no longer evident when oxygen uptake values were considered relative to fat-free mass. Furthermore, cardiopulmonary variables are more affected by exercise intensity than exercise mode, while responses to different intensities are not necessarily proportional. Young adults with excess body fat appear to respond less favorably to acute exercise when compared to lean and average body composition individuals, as evidenced by a longer Tkcal100.

Introduction: Eccentric exercise elicits considerable muscle damage. If a bout of unilateral eccentric exercise is repeated on the ipsilateral or contralateral limb, a repeated bout effect (RBE) may be observed where muscle damage is attenuated. Purpose: To examine whether a RBE exists following repeated bouts of damaging eccentric exercise in the ipsilateral and contralateral limbs, and assess changes to motor unit firing characteristics in both limbs following recovery from an initial bout. Methods: Sixteen untrained men were randomized into exercise (EX) or control (CON) groups. EX performed eccentric exercise of the elbow flexors on the dominant (ipsilateral) limb and repeated the exercise protocol on both ipsilateral and contralateral limbs fourteen days later. Range of motion (ROM), proximal and distal measures of muscle soreness (pVAS/dVAS) and pain-pressure threshold (pPPT/dPPT), maximal isometric torque (MVIC), rate of torque development (RTD) at 50ms (RTD50), 100ms (RTD100), 200ms (RTD200), and peak RTD (RTDpeak) were assessed at baseline (BL), immediately-post (IP), and at twenty-four (24H) and seventy-two hours (72H) post-exercise in EX and CON. Motor unit (MU) firing characteristics were assessed in both limbs via decomposition of surface electromyography (EMG) signals collected during submaximal ramp contractions at 50% and 80% MVIC. Results: Changes in ROM and RTD200 indicated a RBE in both limbs, whereas changes in MVIC and RTD100 indicated a RBE in the ipsilateral limb only. Changes in RTD50, RTDpeak, pPPT, or dPPT did not support a RBE. Increases in the slopes of both the mean firing rate vs. recruitment threshold and the action potential amplitude vs. recruitment threshold relationships at 80% MVIC were noted between bouts for the ipsilateral limb in EX, but not the contralateral limb. Conclusions: Results of this study provide support for a RBE in both limbs, whereas alterations to MU firing characteristics were noted in the ipsilateral limb only.

INTRODUCTION: The critical power (CP) exercise test provides 2 measures, CP and anaerobic working capacity (AWC). CP represents a fatigue threshold that separates the heavy and severe exercise domains, while AWC represents the finite amount of work that can be done above CP. A relatively new protocol for estimating CP has emerged and is described as the 3-minute all-out test (3MT). While this lower body 3MT test has been examined for validity and reliability, very little has been done for the upper body. PURPOSE: Examine the reliability of EP and WEP from the 3MT during upper-body ergometry. This study also compares the traditional CP test vs. 3MT methods for estimating CP and AWC. METHODS: 15 recreationally active men (age: 23 ± 2.6 y; height: 175 ± 4.5 cm; weight: 86.8 ± 14.4 kg; body fat: 20.7 ± 7.8% body fat) completed a graded exercise test to exhaustion on an arm ergometer to determine peak power output (PPO). Participants completed two 3-minute all-out tests (3MT) on different days. Finally, each participant completed three constant work-rate arm-cranking tests at 90, 100, and 110% PPO. Linear regression was used to estimate CP and AWC via the work-time relationship during the constant work-rate tests. EP and WEP were determined using the work-time integral during the 3MT. RESULTS: ICC values for EP (.90) and TW (.956) revealed excellent reliability, while AWC (.783) had good reliability. CP estimated from the traditional method was significantly different from EP estimated from 3MT (t[14] = -3.631; p = 0.003). W' estimated from the traditional method was not significantly different from WEP estimated from 3MT (t[14] = .185; p = .856). CONCLUSIONS: The 3-minute all-out test (3MT) is a reliable method for estimating EP during upper-body ergometry.

Purpose: To examine the maturity-related differences in the adaptations to systemic and localized fatigue thresholds (FTs) in response to sprint interval training (SIT) amongst adolescent male athletes. Methods: Twenty-seven adolescent male athletes, 11-17 years of age, completed pre-testing, six weeks of SIT, and post-testing. Participants were grouped according to their number of years from peak height velocity (PHV), an estimation of somatic maturity status, into PRE ( < -1.5yr), PERI (between -1.5 to +1.5yr) and POST ( > +1.5yr) PHV groups. Each testing session consisted of a ramp exercise protocol on a cycle ergometer. During the protocol, three systemic FTs, gas exchange threshold, ventilatory threshold, and respiratory compensation point were calculated from gas exchange and ventilatory parameters. Also, three localized FTs, neuromuscular fatigue threshold (NFT), deoxyhemoglobin breakpoint (HHbBP), and oxygenation deflection point (OxDP) were calculated from electromyography (NFT) and near-infrared spectroscopy signals (HHbBP and OxDP) from the vastus lateralis of both legs. Data were plotted versus oxygen consumption and 30-second moving averages were calculated. All FTs were determined using the maximal distance method. Localized FTs were averaged between the two legs. The six weeks of SIT consisted of repeated 20-second "all-out" sprints on a cycle ergometer against a load equivalent to 7.5% of body mass with 4-minute rest periods. Maturity-related differences to the adaptations to SIT were assessed with mixed-factorial ANOVA and magnitude-based inferences. Results: During training, POST and PERI completed significantly greater relative work (p=0.003 and p=0.002, respectfully) and peak power (p=0.025 and p=0.023, respectfully) per session than PRE. Furthermore, POST achieved significantly greater peak rotations per minute than PRE (p=0.001) and PERI (p=0.042) during the first training session. No significant group-time interactions existed for absolute V?O2max (p=0.386), relative VO2max (p=0.341) or maximum workload (p=0.593). However, there was a significant group-time interaction (p=0.030) for FTs, with POST having significantly greater changes than PRE (p=0.026) and PERI (p=0.023), and was the only group to experience a significant improvement in FTs from training (p < 0.001). In addition, magnitude based inferences revealed that POST had Likely improvements in all measures of maximal aerobic performance, while PERI only had Likely improvements in maximum workload and PRE experienced Trivial changes. Furthermore, all measured FTs experienced Likely or Very Likely improvements amongst POST; however, PRE and PERI only had improvements in NFT and HHbBP. Conclusion: SIT improved maximal aerobic performance and FTs in POST, but had limited affects in PRE and PERI. The maturity-related differences in the adaptations to SIT may be due to the differences in performance during the training program or underlying physiological changes that occur with maturation.

The primary objective of this study was to evaluate the synergistic effects of repeated sprint training in hypoxia (RSH) and beta-alanine supplementation on performance in recreationally active men. Participants were randomly assigned to one of the following groups: hypoxia + beta-alanine (HB, n = 10), hypoxia + placebo (HP, n = 9), normoxia + beta-alanine (NB, n = 11) and normoxia + placebo (NP, n = 8). All participants completed a total of 8 training sessions (each consisting of 3 sets of 5 × 10-s sprints at a resistance of 7.5% of body mass, with 20-s rest intervals between sprints) over 4 weeks on a cycle ergometer either in hypoxia (Oxygen fraction: FiO2 = 14.2%) or normoxia (FiO2 = 20.9%). Participants were instructed to consume a daily dosage of 6.4g (two 800 mg tablets ingested 4 times per day at 3-4 hour intervals) of either beta-alanine or placebo. Changes in performance in a graded exercise test (GXT), repeated sprint test (RST) and 3-min all-out test (3MT) were examined before and after 28-days of training and supplementation. Aerobic performance was measured by maximal oxygen consumption (VO2max), peak power output (PPO). Exercise intolerance was assessed from critical power (CP), oxygen consumption (VO2RCP) and power output (PRCP) at respiratory compensation point. Exercise capacity was measured by total work (TW) during 3MT. Anaerobic capacity was evaluated via anaerobic working capacity (AWC), heart rate response to RST (RST_HR60) and lactate responses to RST (RST_La) and 3MT (3MT_La). Repeated sprint performance was estimated through average power output of the last sprint (RST_AP5) and all sprints (RST_AP). No between-group differences were observed for training volume or supplementation compliance. Anthropometric and hematological measures remain unchanged before and after intervention in all groups. A main effect of altitude was shown for VO2RCP, PRCP, RST_AP5, RST_HR60, and TW, with post-intervention values in the hypoxia groups significantly (p < 0.05) higher (lower for RST_HR60) than the normoxia groups. A main effect of beta-alanine was detected in AWC, with post-intervention values in the beta-alanine groups being significantly (p < 0.05) higher than the placebo groups. Results of this investigation demonstrated that RSH and beta-alanine benefit performance from different perspectives. RSH improved aerobic performance, exercise tolerance, cardiovascular recovery and exercise capacity, while beta-alanine supplementation maintained anaerobic working capacity in recreationally-trained men during the four-week repeated sprint training intervention.

Strength adaptations from short-term resistance training are thought to be related primarily to neurological adaptations. Considering brain-derived neurotrophic factor (BDNF) role in the nervous system, it is possible that BDNF has a role in these adaptations. Fourteen untrained males were randomized into either a resistance training (RT; n =8) or control (CON; n=6) group. Motor unit (MU) recruitment at 50% and 80% of each participant's maximal voluntary isometric contraction (MVIC), muscle cross sectional area (CSA) and thickness (MT), as well as one-repetition maximum (1RM) of the squat (SQT), leg press (LP), and leg extension (LE) were performed before (PRE) and after (POST) the training period. Following the MU assessment, the recruitment threshold (RT; % MVIC) and mean firing rate (MFR; pulse per second [pps]) of each MU were determined. Linear regression was used to quantify the slope (pps/% MVIC) and y-intercept (pps) of the MFR versus RT relationship for each participant and time point. Participants completed an acute resistance exercise bout at PRE and POST consisting of 3 sets of 8 – 10 repetitions with 90 seconds of rest between each set of SQT, LP, and LE. Blood samples were obtained following a 4-hour fast before (BL), immediately-(IP), and one-(1H) hour post resistance exercise. RT subjects performed the same resistance exercise protocol at PRE twice a week for 3-weeks. CON subjects were instructed to not perform any resistance exercise. Area under the curve (AUC) analysis was determined by the trapezoidal method. Pearson product-moment correlations were used to examine selected bivariate relationships. The ΔBDNF AUC was significantly correlated to the relative 80% Δy-intercept (r=-0.626, p=0.030), and trended to be correlated to the relative 80% Δslope (r=0.551, p=0.063). Our results indicate that Δ in plasma BDNF concentrations appear to be related to Δ's MU recruitment at high intensities (80% of MVIC) of exercise.

Post-activation potentiation (PAP) has been shown to improve acute power-based performance, and the potential to enhance rowing performance. To examine PAP effects with rowing performance, 40 collegiate female rowers performed isometric potentiating (ISO), dynamic potentiating (DYN) and typical control (CON) warm-up protocols, after which they completed a three-minute all-out test (3MT) to evaluate their total distance, peak power, mean power, critical power, anaerobic working capacity (W') and stroke rate. Fifteen-second splits for distance and mean power were also analyzed. The PAP protocols were performed on a rowing ergometer, in a movement pattern that simulated rowing. ISO consisted of 5 × 5-second static muscle actions with the ergometer handle rendered immovable with a nylon boat-strap, while DYN consisted of 2 × 10-second all-out rowing bouts, separated by a 2-minute rest interval. A two-way (condition by experience level) interaction was found for distance, mean power and W' with significant differences (DYN > CON; 5.6 m, 5.9W and 1561.6 J) for more experienced rowers ( > 3.75 years; n=19) and no differences for less experienced rowers (n=18). A main effect for stroke rate was found with DYN > CON (1 s/min). Split analysis of mean power output revealed a two-way (condition by 15s split) interaction independent from experience level. Mean power in DYN was significantly greater than CON and ISO in the 15-30, 30-45, 45-60 and 60-75 second intervals. These results suggest that dynamic PAP may be beneficial for experienced rowers and that these strategies might benefit a greater power output over shorter distances regardless of experience. Future studies should investigate potential benefits of this protocol over a full race distance and identify the difference between experienced and less experienced rowers.

PURPOSE: To compare potential differences in mechanical and physical characteristics of knee flexors and extensors in collegiate male soccer players following different warm up protocols. METHODS: Sixteen collegiate male soccer players (20.33 ± 1.33 years, 176.97 ± 6.72 cm, and 78.43 ± 7.42 kg) participated in this study. A small sided games warm up (SSG), a dynamic warm up (DYN), and a plyometric warm up (PLY) were completed using a randomized crossover design. Tensiomyography (TMG) was used to assess contraction time (Tc), delay time (Td) and maximal displacement (Dm) of the rectus femoris (RF) and biceps femoris (BF) of both legs before (PRE) and after (POST) each warm up. POST assessment included: TMG of the RF and BF, countermovement jump height (CMJ-h), CMJ flight time (CMJ-ft), 20m sprint time (20m), T-test time, and sit and reach (SR) distance. All TMG measures were analyzed using a three-way [condition × time x leg] analysis of variance (ANOVA). All performance variable data were analyzed with a repeated measures ANOVA. RESULTS: There was no difference between warm up protocols for T-test, CMJ-h, or CMJ-ft. 20m significantly improved following SSG (p=0.020) compared to DYN and PLY. SR was significantly greater following PLY (p=0.022). Three-way ANOVA did not reveal a significant interaction for any of the measured TMG variables. However, main effects of time were seen PRE to POST for BF-Tc (p=0.035), RF-Td (p < 0.001) and BF-Td, (p=0.008) and a main effect of condition was seen for RF-Tc (p=0.038). CONCLUSION: Warm-up specific improvements were demonstrated in sprint speed and flexibility measures following SSG and PLY, respectively. While no differences were shown between the examined protocols, the present study revealed PRE to POST changes in certain TMG measures (RF-Td, BF-Td, and BF-Tc) following a warm up in male collegiate soccer athletes.

The primary purpose of this study was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2, n = 11) or four minutes of rest (10:4, n = 11), or 30s work bouts with four minutes of rest (30:4, n = 10)] or a control group (CON, n = 10). Participants underwent six training sessions over two weeks with four to six 'all-out' sprints. During pre- and post-intervention visits, participants underwent a graded exercise test to determine maximal oxygen consumption (VO2peak) and peak power output (PPO), four constant-work rate trials to determine critical power (CP), anaerobic working capacity (W'), and electromyographic fatigue threshold (EMGFT), and an upper body Wingate test to determine peak power (PP), mean power (MP), and total work (TW). Oxygen consumption and blood lactate during the Wingate test generated estimates of oxidative, glycolytic, and ATP-PCr energy system provisions. An analysis of covariance was performed on all testing measurements collected at post with the associated pre-values used as covariates. VO2peak was greater in 30:4 (p = .007) and 10:2 (p = .036) compared to CON and PPO was greater in 30:4 than CON (p = .007). No differences were observed between groups in CP (p = .530), W' (p = .900), EMGFT (p = .692), PP (p = .692), MP (p = .290), or TW (p = .291). Relative energy contribution (p = .026) and energy expenditure (p = .019) of the ATP-PCr energy system was greater in 10:4 compared to CON. SIT protocols with larger work-to-rest ratios induce enhanced aerobic adaptions, whereas smaller work-to-rest ratios may enhance ATP-PCr utilization in the upper body over a short-term two-week intervention.

Traditionally, post-exercise muscular alterations have been examined using invasive techniques that lack the ability to single out individual muscle groups. Sonomyography, tensiomyography, and electrical impedance myography allow for noninvasive skeletal muscle assessment. This project aimed to examine changes in muscle contractility and composition that occur in the early stages of recovery following unaccustomed exercise. METHODS: Twenty-one untrained adults (21.9 ± 1.9 y) performed exercise – 10 × 10 maximal eccentric knee extensions – with their nondominant leg. For each repetition, participants moved through 90° range of motion at 90°•s-1 with a passive return to the start position. Each set was separated by 60 seconds of rest. Sonomyography, tensiomyography, electrical impedance myography, and maximal isometric contractions of the knee extensors (RF & VL) of both legs were performed before (BL), immediately after (IP), and 24 hours post-exercise (24H). RESULTS: Peak torque and rate of torque development were unaltered in response to the eccentric protocol. Significant limb × time interactions were noted for reactance, phase angle, and delay time of the exercised VL, and echo intensity of the exercised RF. Compared to the dominant leg, the nondominant leg displayed significantly greater changes (p < 0.05) in VL delay time and RF echo intensity at IP. Following exercise, bilateral alterations were identified for reactance, phase angle, maximal displacement, delay time, contraction velocity, cross-sectional area, and thickness of the RF, as well as resistance, echo intensity, cross-sectional area, and thickness of the VL. No between-sex differences were noted in response to exercise. CONCLUSIONS: In the absence of performance decrements, sonomyography, tensiomyography, and electrical impedance myography successfully detected acute changes in skeletal muscle composition and function following an acute bout of eccentric exercise in untrained men and women. While the exercised leg exhibited specific responses in delay time and echo intensity, bilateral changes are theorized to have occurred due to contralateral stabilization of the non-exercised leg. The current results suggest that different muscle actions (i.e., eccentric and isometric) promote similar consequences to muscle strength, size, echogenicity, contractility, and bioelectrical properties.