Effects of previous dynamic arm exercise on power output during repeated maximal sprint cycling

The contribution of energy systems during 30-second lower body Wingate anaerobic test in combat sports athletes: Intermittent versus single forms and gender comparison

Combat sports, encompassing a range of activities from striking and grappling to mixed and weapon-based disciplines, have witnessed a surge in popularity worldwide. These sports are demanding, requiring athletes to harness energy from different metabolic pathways to perform short, high-intensity activities interspersed with periods of lower intensity. While it is established that the anaerobic alactic (ATP-PC) and anaerobic lactic systems are pivotal for high-intensity training sessions typical in combat sports, the precise contribution of these systems, particularly in varied training modalities such as single (SMT) and intermittent (IST) forms of the 30-second Wingate test, remains inadequately explored. This study aims at comparing performance outputs, physiological responses and gender differences during the SMT and IST forms of the 30-second Wingate test. Thirty-three highly trained combat sports athletes (17 women, 16 men; 10 boxing, 8 wrestling, 8 taekwondo and 7 karate) randomly performed SMT and IST. The IST consisted of three 10-second all-out attempts separated by 30 seconds of passive recovery, whereas the SMT was a single 30-second maximal effort. Resting, exercise and post-exercise oxygen uptake and peak blood lactate value were used to determine the metabolic energy demands via the PCr-LA-O2 method. The findings showed that total metabolic energy expenditure (TEE), ATP-PCr system contribution and the output of mechanical variables were higher in the IST than in the SMT form (all p<0.001). In contrast, the contribution of glycolytic and oxidative systems was higher in the SMT form (all p<0.001). However, exercise form and gender interaction were not significant (p>0.05). In combat sports, performance is not only determined by physiological and technical skills but also by metabolic energy input and efficiency. Therefore, our results can provide a comparison regarding the effects of exercise type and gender on metabolic energy metabolism to design the training of combat sports athletes.

Identifying the Optimal Arm Priming Exercise Intensity to Improve Maximal Leg Sprint Cycling Performance

Priming exercises improve subsequent motor performance; however, their effectiveness may depend on the workload and involved body areas. The present study aimed to estimate the effects of leg and arm priming exercises performed at different intensities on maximal sprint cycling performance. Fourteen competitive male speed-skaters visited a lab eight times, where they underwent a body composition measurement, two V̇O_2max measurements (leg and arm ergometers), and five sprint cycling sessions after different priming exercise conditions. The five priming exercise conditions included 10-minute rest (Control); 10-minute arm ergometer exercise at 20% V̇O_2max (Arm 20%); 10-minute arm ergometer exercise at 70% V̇O_2max (Arm 70%); 1-min maximal arm ergometer exercise at 140% V̇O_2max (Arm 140%); and 10-min leg ergometer exercise at 70% V̇O_2max (Leg 70%). Power outputs of 60-s maximal sprint cycling, blood lactate concentration, heart rate, muscle and skin surface temperature, and rating of perceived exertion were compared between the priming conditions at different measurement points. Our results showed that the Leg 70% was the optimal priming exercise among our experimental conditions. Priming exercise with the Arm 70% also tended to improve subsequent motor performance, while Arm 20% and Arm 140% did not. Mild elevation in blood lactate concentration by arm priming exercise may improve the performance of high-intensity exercise.

Effects of Oral Creatine Supplementation on Power Output during Repeated Treadmill Sprinting

The aim of the present study was to examine the effects of creatine (Cr) supplementation on power output during repeated sprints on a non-motorized treadmill. Sixteen recreationally active males volunteered for this study (age 25.5 ± 4.8 y, height 179 ± 5 cm, body mass 74.8 ± 6.8 kg). All participants received placebo supplementation (75 mg of glucose·kg^-1·day^-1) for 5 days and then performed a baseline repeated sprints test (6 × 10 s sprints on a non-motorised treadmill). Thereafter, they were randomly assigned into a Cr (75 mg of Cr monohydrate·kg^-1·day^-1) or placebo supplementation, as above, and the repeated sprints test was repeated. After Cr supplementation, body mass was increased by 0.99 ± 0.83 kg (p = 0.007), peak power output and peak running speed remained unchanged throughout the test in both groups, while the mean power output and mean running speed during the last 5 s of the sprints increased by 4.5% (p = 0.005) and 4.2% to 7.0%, respectively, during the last three sprints (p = 0.005 to 0.001). The reduction in speed within each sprint was also blunted by 16.2% (p = 0.003) following Cr supplementation. Plasma ammonia decreased by 20.1% (p = 0.037) after Cr supplementation, despite the increase in performance. VO₂ and blood lactate during the repeated sprints test remained unchanged after supplementation, suggesting no alteration of aerobic or glycolytic contribution to adenosine triphosphate production. In conclusion, Cr supplementation improved the mean power and speed in the second half of a repeated sprint running protocol, despite the increased body mass. This improvement was due to the higher power output and running speed in the last 5 s of each 10 s sprint.

Effect of Short-Duration High-Intensity Upper-Body Pre-Load Component on Performance among High-Level Cyclists

The aim of the present study was to evaluate the effects of upper-body high-intensity exercise priming on subsequent leg exercise performance. Specifically, to compare maximal 4000 m cycling performance with upper-body pre-load (MPThigh) and common warm-up (MPTlow). In this case, 15 high-level cyclists (23.3 ± 3.6 years; 181 ± 7 cm; 76.2 ± 10.0 kg; V˙O2max: 65.4 ± 6.7 mL·kg−1·min−1) participated in the study attending three laboratory sessions, completing an incremental test and both experimental protocols. In MPThigh, warm-up was added by a 25 s high-intensity all-out arm crank effort to the traditional 20-min aerobic warm-up. Both 4000 m maximal bouts started with a 12 s all-out start. Heart rate, blood lactate concentration [La) and spirometric data were measured and analyzed. Overall MPThigh time was slower by 5.3 ± 1.2 s (p < 0.05). [La] at the start was 5.5 ± 1.5 mmol·L−1 higher for MPThigh (p < 0.001) reducing anaerobic energy contribution which was higher in MPTlow during the first and third 1000 m split (p < 0.05). Similarly, MPTlow maintained higher total average power during the entire performance (p < 0.05, d = 0.7). Although the MPThigh condition performed less effectively due to decreased anaerobic capacity, pre-load effect may have the potential to enhance performance at longer distances.

Can We Improve the Functional Threshold Power Test by Adding High-Intensity Priming Arm-Crank?

The aim of the present study was to evaluate the effects of arm-crank induced priming on subsequent 20 min Functional Threshold Power Test among 11 well-trained male cyclists (18.8 ± 0.9 years; 182 ± 5 cm; 73.0 ± 6.6 kg; V˙O2max 67.9 ± 5.1 mL·kg-1·min-1). Participants completed an incremental test and two maximal performance tests (MPTs) in a randomized order. Warm-up prior to MPTlow consisted of 20 min aerobic exercise and 25 s high-intensity all-out arm crank effort was added to warm-up in MPThigh. Constant intensities for the first 17 min of MPT were targeting to achieve a similar relative fatigue according to participants' physiological capacity before the last 3 min all-out spurt. Final 3 min all-out spurt power was 4.94 ± 0.27 W·kg-1 and 4.85 ± 0.39 W·kg-1 in MPTlow and MPThigh, respectively (not statistically different: p = 0.116; d = 0.5). Blood lactate [La] levels just before the start were higher (p < 0.001; d = 2.6) in MPThigh (5.6 ± 0.5 mmol·L-1) compared to MPTlow (1.1 ± 0.1 mmol·L-1). According to V˙CO2 and net [La] data, significantly higher anaerobic energy production was detected among MPTlow condition. In conclusion, priming significantly reduced anaerobic energy contribution but did neither improve nor decrease group mean performance although effects were variable. We suggest priming to have beneficial effects based on previous studies; however, the effects are individual and additional studies are needed to distinguish such detailed effects in single athletes.

Muscle Ionic Shifts During Exercise: Implications for Fatigue and Exercise Performance

Exercise causes major shifts in multiple ions (e.g., K⁺ , Na⁺ , H⁺ , lactate^- , Ca²⁺ , and Cl^- ) during muscle activity that contributes to development of muscle fatigue. Sarcolemmal processes can be impaired by the trans-sarcolemmal rundown of ion gradients for K⁺ , Na⁺ , and Ca²⁺ during fatiguing exercise, while changes in gradients for Cl^- and Cl^- conductance may exert either protective or detrimental effects on fatigue. Myocellular H⁺ accumulation may also contribute to fatigue development by lowering glycolytic rate and has been shown to act synergistically with inorganic phosphate (Pi) to compromise cross-bridge function. In addition, sarcoplasmic reticulum Ca²⁺ release function is severely affected by fatiguing exercise. Skeletal muscle has a multitude of ion transport systems that counter exercise-related ionic shifts of which the Na⁺ /K⁺ -ATPase is of major importance. Metabolic perturbations occurring during exercise can exacerbate trans-sarcolemmal ionic shifts, in particular for K⁺ and Cl^- , respectively via metabolic regulation of the ATP-sensitive K⁺ channel (K_ATP ) and the chloride channel isoform 1 (ClC-1). Ion transport systems are highly adaptable to exercise training resulting in an enhanced ability to counter ionic disturbances to delay fatigue and improve exercise performance. In this article, we discuss (i) the ionic shifts occurring during exercise, (ii) the role of ion transport systems in skeletal muscle for ionic regulation, (iii) how ionic disturbances affect sarcolemmal processes and muscle fatigue, (iv) how metabolic perturbations exacerbate ionic shifts during exercise, and (v) how pharmacological manipulation and exercise training regulate ion transport systems to influence exercise performance in humans. © 2021 American Physiological Society. Compr Physiol 11:1895-1959, 2021.

The Effect of Lower Body Anaerobic Pre-Loading on Upper Body Ergometer Time Trial Performance

Pre-competitive conditioning has become a substantial part of successful performance. In addition to temperature changes, a metabolic conditioning can have a significant effect on the outcome, although the right dosage of such a method remains unclear. The main goal of the investigation was to measure how a lower body high-intensity anaerobic cycling pre-load exercise (HIE) of 25 s affects cardiorespiratory and metabolic responses in subsequent upper body performance. Thirteen well-trained college-level male cross-country skiers (18.1 ± 2.9 years; 70.8 ± 7.6 kg; 180.6 ± 4.7 cm; 15.5 ± 3.5% body fat) participated in the study. The athletes performed a 1000-m maximal double-poling upper body ergometer time trial performance test (TT) twice. One TT was preceded by a conventional low intensity warm-up (TT_low) while additional HIE cycling was performed 9 min before the other TT (TT_high). Maximal double-poling performance after the TT_low (225.1 ± 17.6 s) was similar (p > 0.05) to the TT_high (226.1 ± 15.7 s). Net blood lactate (La) increase (delta from end of TT minus start) from the start to the end of the TT_low was 10.5 ± 2.2 mmol L⁻¹ and 6.5 ± 3.4 mmol L⁻¹ in TT_high (p < 0.05). La net changes during recovery were similar for both protocols, remaining 13.5% higher in TT_high group even 6 min after the maximal test. VCO₂ was lower (p < 0.05) during the last 400-m split in TT_high, however during the other splits no differences were found (p < 0.05). Respiratory exchange ratio (RER) was significantly lower in TT_high in the third, fourth and the fifth 200 m split. Participants individual pacing strategies showed high relation (p < 0.05) between slower start and faster performance. In conclusion, anaerobic metabolic pre-conditioning leg exercise significantly reduced net-La increase, but all-out upper body performance was similar in both conditions. The pre-conditioning method may have some potential but needs to be combined with a pacing strategy different from the usual warm-up procedure.

Non-local Muscle Fatigue Effects on Muscle Strength, Power, and Endurance in Healthy Individuals: A Systematic Review with Meta-analysis

BACKGROUND

The fatigue of a muscle or muscle group can produce global responses to a variety of systems (i.e., cardiovascular, endocrine, and others). There are also reported strength and endurance impairments of non-exercised muscles following the fatigue of another muscle; however, the literature is inconsistent.

OBJECTIVE

To examine whether non-local muscle fatigue (NLMF) occurs following the performance of a fatiguing bout of exercise of a different muscle(s).

DESIGN

Systematic review and meta-analysis.

SEARCH AND INCLUSION

A systematic literature search using a Boolean search strategy was conducted with PubMed, SPORTDiscus, Web of Science, and Google Scholar in April 2020, and was supplemented with additional 'snowballing' searches up to September 2020. To be included in our analysis, studies had to include at least one intentional performance measure (i.e., strength, endurance, or power), which if reduced could be considered evidence of muscle fatigue, and also had to include the implementation of a fatiguing protocol to a location (i.e., limb or limbs) that differed to those for which performance was measured. We excluded studies that measured only mechanistic variables such as electromyographic activity, or spinal/supraspinal excitability. After search and screening, 52 studies were eligible for inclusion including 57 groups of participants (median sample = 11) and a total of 303 participants.

RESULTS

The main multilevel meta-analysis model including all effects sizes (278 across 50 clusters [median = 4, range = 1 to 18 effects per cluster) revealed a trivial point estimate with high precision for the interval estimate [- 0.02 (95% CIs = - 0.14 to 0.09)], yet with substantial heterogeneity (Q₍₂₇₇₎ = 642.3, p < 0.01), I² = 67.4%). Subgroup and meta-regression analyses showed that NLMF effects were not moderated by study design (between vs. within-participant), homologous vs. heterologous effects, upper or lower body effects, participant training status, sex, age, the time of post-fatigue protocol measurement, or the severity of the fatigue protocol. However, there did appear to be an effect of type of outcome measure where both strength [0.11 (95% CIs = 0.01-0.21)] and power outcomes had trivial effects [- 0.01 (95% CIs = - 0.24 to 0.22)], whereas endurance outcomes showed moderate albeit imprecise effects [- 0.54 (95% CIs = - 0.95 to - 0.14)].

CONCLUSIONS

Overall, the findings do not support the existence of a general NLMF effect; however, when examining specific types of performance outcomes, there may be an effect specifically upon endurance-based outcomes (i.e., time to task failure). However, there are relatively fewer studies that have examined endurance effects or mechanisms explaining this possible effect, in addition to fewer studies including women or younger and older participants, and considering causal effects of prior training history through the use of longitudinal intervention study designs. Thus, it seems pertinent that future research on NLMF effects should be redirected towards these still relatively unexplored areas.

Unilateral Quadriceps Fatigue Induces Greater Impairments of Ipsilateral versus Contralateral Elbow Flexors and Plantar Flexors Performance in Physically Active Young Adults

Non-local muscle fatigue (NLMF) studies have examined crossover impairments of maximal voluntary force output in non-exercised, contralateral muscles as well as comparing upper and lower limb muscles. Since prior studies primarily investigated contralateral muscles, the purpose of this study was to compare NLMF effects on elbow flexors (EF) and plantar flexors (PF) force and activation (electromyography: EMG). Secondly, possible differences when testing ipsilateral or contralateral muscles with a single or repeated isometric maximum voluntary contractions (MVC) were also investigated. Twelve participants (six males: (27.3 ± 2.5 years, 186.0 ± 2.2 cm, 91.0 ± 4.1 kg; six females: 23.0 ± 1.6 years, 168.2 ± 6.7 cm, 60.0 ± 4.3 kg) attended six randomized sessions where ipsilateral or contralateral PF or EF MVC force and EMG activity (root mean square) were tested following a dominant knee extensors (KE) fatigue intervention (2×100s MVC) or equivalent rest (control). Testing involving a single MVC (5s) was completed by the ipsilateral or contralateral PF or EF prior to and immediately post-interventions. One minute after the post-intervention single MVC, a 12×5s MVCs fatigue test was completed. Two-way repeated measures ANOVAs revealed that ipsilateral EF post-fatigue force was lower (-6.6%, p = 0.04, d = 0.18) than pre-fatigue with no significant changes in the contralateral or control conditions. EF demonstrated greater fatigue indexes for the ipsilateral (9.5%, p = 0.04, d = 0.75) and contralateral (20.3%, p < 0.01, d = 1.50) EF over the PF, respectively. There were no significant differences in PF force, EMG or EF EMG post-test or during the MVCs fatigue test. The results suggest that NLMF effects are side and muscle specific where prior KE fatigue could hinder subsequent ipsilateral upper body performance and thus is an important consideration for rehabilitation, recreation and athletic programs.

Effects of Prior Upper Body Exercise on the 3-min All-Out Cycling Test in Men

INTRODUCTION

Prior upper body exercise reduces the curvature constant (W') of the hyperbolic power-duration relationship without affecting critical power. This study tested the hypothesis that prior upper body exercise reduces the work done over the end-test power (WEP; analog of W') during a 3-min all-out cycling test (3MT) without affecting the end-test power (EP; analog of critical power).

METHODS

Ten endurance-trained men (V˙O2max = 62 ± 5 mL·kg·min) performed a 3MT without (CYC) and with (ARM-CYC) prior severe-intensity, intermittent upper body exercise. EP was calculated as the mean power output over the last 30 s of the 3MT, whereas WEP was calculated as the power-time integral above EP.

RESULTS

At the start of the 3MT, plasma [La] (1.8 ± 0.4 vs 14.1 ± 3.4 mmol·L) and [H] (42.8 ± 3.1 vs 58.6 ± 5.5 nmol·L) were higher, whereas the strong ion difference (41.4 ± 2.2 vs 30.9 ± 4.6 mmol·L) and [HCO3] (27.0 ± 1.9 vs 16.9 ± 3.2 mmol·L) were lower during ARM-CYC than CYC (P < 0.010). EP was 12% lower during the 3MT of ARM-CYC (298 ± 52 W) than CYC (338 ± 60 W; P < 0.001), whereas WEP was not different (CYC: 12.8 ± 3.3 kJ vs ARM-CYC: 13.5 ± 4.1 kJ, P = 0.312). EP in CYC was positively correlated with the peak [H] (r = 0.78, P = 0008) and negatively correlated with the lowest [HCO3] (r = -0.74, P = 0.015).

CONCLUSIONS

These results suggest that EP during a 3MT in endurance-trained men is sensitive to fatigue-related ionic perturbation.

Monitoring Exercise-Induced Muscle Fatigue and Adaptations: Making Sense of Popular or Emerging Indices and Biomarkers

Regular exercise with the appropriate intensity and duration may improve an athlete’s physical capacities by targeting different performance determinants across the endurance–strength spectrum aiming to delay fatigue. The mechanisms of muscle fatigue depend on exercise intensity and duration and may range from substrate depletion to acidosis and product inhibition of adenosinetriphosphatase (ATPase) and glycolysis. Fatigue mechanisms have been studied in isolated muscles; single muscle fibers (intact or skinned) or at the level of filamentous or isolated motor proteins; with each approach contributing to our understanding of the fatigue phenomenon. In vivo methods for monitoring fatigue include the assessment of various functional indices supported by the use of biochemical markers including blood lactate levels and more recently redox markers. Blood lactate measurements; as an accompaniment of functional assessment; are extensively used for estimating the contribution of the anaerobic metabolism to energy expenditure and to help interpret an athlete’s resistance to fatigue during high intensity exercise. Monitoring of redox indices is gaining popularity in the applied sports performance setting; as oxidative stress is not only a fatigue agent which may play a role in the pathophysiology of overtraining syndrome; but also constitutes an important signaling pathway for training adaptations; thus reflecting training status. Careful planning of sampling and interpretation of blood biomarkers should be applied; especially given that their levels can fluctuate according to an athlete’s lifestyle and training histories.

Performance Enhancing Effect of Metabolic Pre-conditioning on Upper-Body Strength-Endurance Exercise

High systemic blood lactate (La) was shown to inhibit glycolysis and to increase oxidative metabolism in subsequent anaerobic exercise. Aim of this study was to examine the effect of a metabolic pre-conditioning (MPC) on net La increase and performance in subsequent pull-up exercise (PU). Nine trained students (age: 25.1 ± 1.9 years; BMI: 21.7 ± 1.4) performed PU on a horizontal bar with legs placed on a box (angular hanging) either without or with MPC in a randomized order. MPC was a 26.6 ± 2 s all out shuttle run. Each trial started with a 15-min warm-up phase. Time between MPC and PU was 8 min. Heart rate (HR) and gas exchange measures (VO₂, VCO₂, and VE) were monitored, La and glucose were measured at specific time points. Gas exchange measures were compared by area under the curve (AUC). In PU without MPC, La increased from 1.24 ± 0.4 to 6.4 ± 1.4 mmol⋅l^-1, whereas with MPC, PU started at 9.28 ± 1.98 mmol⋅l^-1 La which increased to 10.89 ± 2.13 mmol⋅l^-1. With MPC, net La accumulation was significantly reduced by 75.5% but performance was significantly increased by 1 rep (4%). Likewise, net oxygen uptake VO₂ (50% AUC), pulmonary ventilation (VE) (34% AUC), and carbon dioxide VCO₂ production (26% AUC) were significantly increased during PU but respiratory exchange ratio (RER) was significantly blunted during work and recovery. MPC inhibited glycolysis and increased oxidative metabolism and performance in subsequent anaerobic upper-body strength-endurance exercise.

Cancer and Exercise: Warburg Hypothesis, Tumour Metabolism and High-Intensity Anaerobic Exercise

There is ample evidence that regular moderate to vigorous aerobic physical activity is related to a reduced risk for various forms of cancer to suggest a causal relationship. Exercise is associated with positive changes in fitness, body composition, and physical functioning as well as in patient-reported outcomes such as fatigue, sleep quality, or health-related quality of life. Emerging evidence indicates that exercise may also be directly linked to the control of tumour biology through direct effects on tumour-intrinsic factors. Beside a multitude of effects of exercise on the human body, one underscored effect of exercise training is to target the specific metabolism of tumour cells, namely the Warburg-type highly glycolytic metabolism. Tumour metabolism as well as the tumour–host interaction may be selectively influenced by single bouts as well as regularly applied exercise, dependent on exercise intensity, duration, frequency and mode. High-intensity anaerobic exercise was shown to inhibit glycolysis and some studies in animals showed that effects on tumour growth might be stronger compared with moderate-intensity aerobic exercise. High-intensity exercise was shown to be safe in patients; however, it has to be applied carefully with an individualized prescription of exercise.

The Effect of Previous Wingate Performance Using one Body Region on Subsequent Wingate Performance Using a Different Body Region

The 30 second Wingate Anaerobic Test (WAnT) is the gold standard measure of anaerobic performance. The present investigation aimed to determine if a previous WAnT using one body region significantly affected a subsequent WAnT using a different body region. Twelve male university students (n = 12, 23 ± 2 years, 84 ± 16.1 kg, 178.5 ± 7.4 cm) volunteered to complete two repeated WAnT protocols (either lower body WAnT followed by an upper body WAnT or vice versa) on two separate testing occasions. The upper body WAnT was conducted on a modified electromagnetically braked cycle ergometer using a flywheel braking force corresponding to 5% bodyweight. The lower body WAnT was conducted on an electronically braked cycle ergometer using a flywheel braking force corresponding to 7.5% bodyweight. Participants had a 1 minute rest period for transition between WAnTs. Data are reported as mean ± standard deviation. No significant differences were identified in power indices for the lower body between 30 s WAnTs. When the upper body WAnT was performed 2nd, absolute peak power (p < 0.01), mean power (p < 0.001) and relative mean power (p < 0.001) were significantly lower compared to when the upper body WAnT was performed 1st. The value of maximum revolutions per minute was significantly lower (p < 0.001) when the upper body WAnT was performed after the lower body WAnT, compared to when it was performed 1st (193.3 ± 11.4 1st vs 179.8 ± 14.4 2nd). Previous upper body sprint exercise does not significantly affect lower body sprint exercise; however, previous lower body sprint exercise severely compromises subsequent upper body sprint performance.

Peripheral and central fatigue after high intensity resistance circuit training

INTRODUCTION

The aim of this study was to investigate the effects of high intensity resistance circuit (HIRC) and traditional strength training (TST) on neuromuscular fatigue and metabolic responses.

METHODS

Twelve trained young subjects performed HIRC and TST in a counterbalanced order with 1 week rest in-between. The amount of workload and the inter-set time for each local muscle group were matched (180 s), however, the time between successive exercises differed. The twitch interpolation technique was used to test neuromuscular function of the knee extensor muscles. Blood lactate concentration was used to evaluate metabolic responses.

RESULTS

Maximum voluntary contraction and resting potentiated twitch amplitude (Q_tw ) were significantly reduced after HIRC, but there were not changes after TST, while reductions in voluntary activation were similar. Lactate concentration increased significantly more after HIRC.

CONCLUSIONS

The higher lactate concentration after HIRC probably impaired excitation-contraction coupling, indicating larger peripheral fatigue than after TST. Muscle Nerve 56: 152-159, 2017.

Locomotor muscle fatigue is not critically regulated after prior upper body exercise

This study examined the effects of prior upper body exercise on subsequent high-intensity cycling exercise tolerance and associated changes in neuromuscular function and perceptual responses. Eight men performed three fixed work-rate (85% peak power) cycling tests: 1) to the limit of tolerance (CYC); 2) to the limit of tolerance after prior high-intensity arm-cranking exercise (ARM-CYC); and 3) without prior exercise and for an equal duration as ARM-CYC (ISOTIME). Peripheral fatigue was assessed via changes in potentiated quadriceps twitch force during supramaximal electrical femoral nerve stimulation. Voluntary activation was assessed using twitch interpolation during maximal voluntary contractions. Cycling time during ARM-CYC and ISOTIME (4.33 ± 1.10 min) was 38% shorter than during CYC (7.46 ± 2.79 min) (P < 0.001). Twitch force decreased more after CYC (-38 ± 13%) than ARM-CYC (-26 ± 10%) (P = 0.004) and ISOTIME (-24 ± 10%) (P = 0.003). Voluntary activation was 94 ± 5% at rest and decreased after CYC (89 ± 9%, P = 0.012) and ARM-CYC (91 ± 8%, P = 0.047). Rating of perceived exertion for limb discomfort increased more quickly during cycling in ARM-CYC [1.83 ± 0.46 arbitrary units (AU)/min] than CYC (1.10 ± 0.38 AU/min, P = 0.003) and ISOTIME (1.05 ± 0.43 AU/min, P = 0.002), and this was correlated with the reduced cycling time in ARM-CYC (r = -0.72, P = 0.045). In conclusion, cycling exercise tolerance after prior upper body exercise is potentially mediated by central fatigue and intolerable levels of sensory perception rather than a critical peripheral fatigue limit.

The effect of prior upper body exercise on subsequent wingate performance

It has been reported previously that the upper body musculature is continually active during high intensity cycle ergometry. The aim of this study was to examine the effects of prior upper body exercise on subsequent Wingate (WAnT) performance. Eleven recreationally active males (20.8 ± 2.2 yrs; 77.7 ± 12.0 kg; 1.79 ± 0.04 m) completed two trials in a randomised order. In one trial participants completed 2 × 30 s WAnT tests (WAnT1 and WAnT2) with a 6 min recovery period; in the other trial, this protocol was preceded with 4 sets of biceps curls to induce localised arm fatigue. Prior upper body exercise was found to have a statistically significant detrimental effect on peak power output (PPO) during WAnT1 (P < 0.05) but no effect was observed for mean power output (MPO) (P > 0.05). Handgrip (HG) strength was also found to be significantly lower following the upper body exercise. These results demonstrate that the upper body is meaningfully involved in the generation of leg power during intense cycling.

The measurement of maximal (anaerobic) power output on a cycle ergometer: a critical review

The interests and limits of the different methods and protocols of maximal (anaerobic) power (Pmax) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of Pmax during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting Pmax in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices.

The contribution of energy systems during the upper body Wingate anaerobic test

The purpose of this study was to measure the contribution of the aerobic, anaerobic lactic, and alactic systems during an upper body Wingate Anaerobic test (WAnT). Oxygen uptake and blood lactate were measured before, during, and after the WAnT and body composition analyzed by dual-energy X-ray absorptiometry. The contribution of the energy systems was 11.4% ± 1.4%, 60.3% ± 5.6%, and 28.3% ± 4.9% for the aerobic, anaerobic lactic, and alactic systems, respectively.

Effect of a prior force-velocity test performed with legs on subsequent peak power output measured with arms or vice versa

The aim of this study was to examine whether measurement of peak anaerobic power (Wpeak) by force-velocity test using the arms or the legs influenced the performance obtained when the opposite muscle group was tested. Ten trained male throwers (age: 20.6 +/- 2; stature: 1.82 +/- 0.06 m; and body mass: 85.5 +/- 17.2 kg) performed, on separate days, 2 Monark cycle-ergometer protocols comprising (a) arm cranking (A1) followed by a leg cycling (L2) force-velocity test (series A-L) and (b) a leg cycling (L1) followed by an arm cranking (A2) force-velocity test (series L-A). On each day, 8 minutes of seated rest separated the 2 force-velocity tests. Arterialized capillary blood was collected from the finger tips for blood lactate analysis at rest and at the end of each force-velocity test. Wpeak-A1 and Wpeak-A2 were similar (8.1 +/- 1.7 and 8.6 +/- 1.5 W.kg, respectively). Wpeak-L1 and Wpeak-L2 were 14.0 +/- 3 and 13.4 +/- 2.8 W.kg (NS). Blood [La] increased significantly after each force-velocity test (p < 0.001), but peak blood [La] did not differ significantly between L1 (6.6 +/- 1.2) and L2 (6.2 +/- 1.4 mmol.L) or between A1 (7.2 +/- 1.0) and A2 (7.4 +/- 1.6 mmol.L). In this population, force-velocity tests performed using the legs or the arms did not induce a significant decrease in force-velocity determinations of peak anaerobic power performed subsequently with the opposite muscle group. In strength-trained athletes, the force-velocity approach can thus be used to measure the peak power output of both the legs and the arms in a single laboratory session, without adversely affecting estimates of an athlete's performance.

Influence of resistive load on power output and fatigue during intermittent sprint cycling exercise in children

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship.

Physiological and metabolic responses of repeated-sprint activities:specific to field-based team sports

Field-based team sports, such as soccer, rugby and hockey are popular worldwide. There have been many studies that have investigated the physiology of these sports, especially soccer. However, some fitness components of these field-based team sports are poorly understood. In particular, repeated-sprint ability (RSA) is one area that has received relatively little research attention until recent times. Historically, it has been difficult to investigate the nature of RSA, because of the unpredictability of player movements performed during field-based team sports. However, with improvements in technology, time-motion analysis has allowed researchers to document the detailed movement patterns of team-sport athletes. Studies that have published time-motion analysis during competition, in general, have reported the mean distance and duration of sprints during field-based team sports to be between 10-20 m and 2-3 seconds, respectively. Unfortunately, the vast majority of these studies have not reported the specific movement patterns of RSA, which is proposed as an important fitness component of team sports. Furthermore, there have been few studies that have investigated the physiological requirements of one-off, short-duration sprinting and repeated sprints (<10 seconds duration) that is specific to field-based team sports. This review examines the limited data concerning the metabolic changes occurring during this type of exercise, such as energy system contribution, adenosine triphosphate depletion and resynthesis, phosphocreatine degradation and resynthesis, glycolysis and glycogenolysis, and purine nucleotide loss. Assessment of RSA, as a training and research tool, is also discussed.

Models to explain fatigue during prolonged endurance cycling

Much of the previous research into understanding fatigue during prolonged cycling has found that cycling performance may be limited by numerous physiological, biomechanical, environmental, mechanical and psychological factors. From over 2000 manuscripts addressing the topic of fatigue, a number of diverse cause-and-effect models have been developed. These include the following models: (i) cardiovascular/anaerobic; (ii) energy supply/energy depletion; (iii) neuromuscular fatigue; (iv) muscle trauma; (v) biomechanical; (vi) thermoregulatory; (vii) psychological/motivational; and (viii) central governor. More recently, however, a complex systems model of fatigue has been proposed, whereby these aforementioned linear models provide afferent feedback that is integrated by a central governor into our unconscious perception of fatigue. This review outlines the more conventional linear models of fatigue and addresses specifically how these may influence the development of fatigue during cycling. The review concludes by showing how these linear models of fatigue might be integrated into a more recently proposed nonlinear complex systems model of exercise-induced fatigue.

Physiological aspects of surfboard riding performance

Surfboard riding (surfing) has experienced a 'boom' in participants and media attention over the last decade at both the recreational and the competitive level. However, despite its increasing global audience, little is known about physiological and other factors related to surfing performance. Time-motion analyses have demonstrated that surfing is an intermittent sport, with arm paddling and remaining stationary representing approximately 50% and 40% of the total time, respectively. Wave riding only accounts for 4-5% of the total time when surfing. It has been suggested that these percentages are influenced mainly by environmental factors. Competitive surfers display specific size attributes. Particularly, a mesomorphic somatotype and lower height and body mass compared with other matched-level aquatic athletes. Data available suggest that surfers possess a high level of aerobic fitness. Upper-body ergometry reveals that peak oxygen uptake (VO2peak) values obtained in surfers are consistently higher than values reported for untrained subjects and comparable with those reported for other upper-body endurance-based athletes. Heart rate (HR) measurements during surfing practice have shown an average intensity between 75% and 85% of the mean HR values measured during a laboratory incremental arm paddling VO2peak test. Moreover, HR values, together with time-motion analysis, suggest that bouts of high-intensity exercise demanding both aerobic and anaerobic metabolism are intercalated with periods of moderate- and low-intensity activity soliciting aerobic metabolism. Minor injuries such as lacerations are the most common injuries in surfing. Overuse injuries in the shoulder, lower back and neck area are becoming more common and have been suggested to be associated with the repetitive arm stroke action during board paddling. Further research is needed in all areas of surfing performance in order to gain an understanding of the sport and eventually to bring surfing to the next level of performance.

Effect of active and passive recovery on blood lactate and performance during simulated competition in high level gymnasts

The purpose of this study was to investigate the effect of two recovery strategies between men's gymnastics events on blood lactate removal (BL) and performance as rated by expert "blind" judges. Twelve male gymnasts (21.8 +/- 2.4 years) participated. The sessions were composed of routine performances in the six Olympic events, which were separated by 10 min of recovery. All gymnasts performed two recovery protocols between events on separate days: Rest protocol, 10 min rest in a sitting position; Combined protocol, 5 min rest and 5 min self-selected active recovery. Three blood samples were taken at 2, 5, and 10 min following each event. Gymnasts produced moderate values of BL following each of the six events (2.2 to 11.6 mmol.L-1). There was moderate variability in BL values between events that could not be accounted for by the athlete's event performance. Gymnasts showed higher BL concentration (p > .05) and significantly (p < .05) higher scoring performances (as rated by a panel of certified judges) when they used a combined recovery between gymnastics events rather than a passive recovery (delta BL = 40.51% vs. 28.76% of maximal BL, p < .05, and total score = 47.28 +/- 6.82 vs. 38.39 +/- 7.55, p < .05, respectively).

Lactate release, concentration in blood, and apparent distribution volume after intense bicycling

To study the release of lactate from muscle and its relationship to the blood lactate concentration during and after intense bicycling, young men cycled at 5.5 W kg(-1) body mass for 2 min to exhaustion or stopped after 1 min (nonexhaustive ride). The leg's release of lactate during and after each ride was taken from the measured blood flow and lactate concentrations in arterial and femoral-venous blood. Muscle biopsies were taken in separate experiments and analyzed for lactate. During the bicycling, 6 to 10% of the lactate produced was released to the blood. During exercise and for the first few minutes after, the rate of lactate release did not differ between 2 min exhaustive and 1 min nonexhaustive bicycling. The integrated release (exercise plus recovery) for the 1 min bicycling was 60 to 80% of the corresponding value of the 2 min exhaustive bicycling. In the late recovery, the blood lactate concentration was 3 to 5 times higher after 2 min exhaustive bicycling than after the 1 min nonexhaustive bicycling. There was thus a mismatch between the amount of lactate released and measured concentration in blood, reflecting a smaller distribution volume after the exhaustive bicycling. The blood lactate concentration may therefore not be a good measure of the lactate production and anaerobic energy release during bicycling.

Power output and muscle metabolism during and following recovery from 10 and 20 s of maximal sprint exercise in humans

On two separate days eight male subjects performed a 10- or 20-s cycle ergometer sprint (randomized order) followed, after 2 min of recovery, by a 30-s sprint. Muscle biopsies were obtained from the vastus lateralis at rest, immediately after the first sprint and after the 2 min of recovery on both occasions. The anaerobic ATP turnover during the initial 10 s of sprint 1 was 129 +/- 12 mmol kg dry weight-1 and decreased to 63 +/- 10 mmol kg dry weight-1 between the 10th and 20th s of sprint 1. This was a result of a 300% decrease in the rate of phosphocreatine breakdown and a 35% decrease in the glycolytic rate. Despite this 51% reduction in anaerobic ATP turnover, the mean power between 10 and 20 s of sprint 1 was reduced by only 28%. During the same period, oxygen uptake increased from 1.30 +/- 0.15 to 2.40 +/- 0.23 L min-1, which partially compensated for the decreased anaerobic metabolism. Muscle pH decreased from 7.06 +/- 0.02 at rest to 6.94 +/- 0.02 after 10 s and 6.82 +/- 0.03 after 20 s of sprinting (for all changes P < 0.01). Muscle pH did not change following a 2-min recovery period after both the 10- and 20-s sprints, but phosphocreatine was resynthesized to 86 +/- 3 and 76 +/- 3% of the resting value, respectively (n.s. 10- vs. 20-s sprint). Following 2 min of recovery after the 10-s sprint subjects were able to reproduce peak but not mean power. Restoration of both mean and peak power following the 20-s sprint was 88% of sprint 1, and was lower compared with that after the 10-s sprint (P < 0.01). Total work during the second 30-s sprint after the 10- and the 20-s sprint was 19.3 +/- 0.6 and 17.8 +/- 0.5 kJ, respectively (P < 0.01). As oxygen uptake was the same during the 30-s sprints (2.95 +/- 0.15 and 3.02 +/- 0.16 L min-1), and (Phosphocreatine) before the sprint was similar, the lower work may be related to a reduced glycolytic ATP regeneration as a result of the higher muscle acidosis.

Effects of drafting during short-track speed skating

Short-track speed skating involves pack-style racing where five to seven skaters may be on the ice at once. Since average speed for a 3000-m event may exceed 35 km.h-1, drafting may be beneficial. However, the short (111 m) oval track could limit effective drafting space, and high forces required in cornering may compromise potential benefits. We evaluated heart rate (HR)-lactate (LA) responses and post-drafting 3-lap sprint performance using 18 National Team and developmental skaters. Two 4-min trials, one drafting and one leading at 8.8 m.s-1, were performed. In addition, six skaters performed three 3-lap sprints, rested, immediately after a 4-min drafting trial at 9.2 m.s-1, and immediately after an unaided 4-min trial at 9.2 m.s-1. Results demonstrated lower HR and LA responses during drafting (174.0 +/- 9.0 and 5.56 +/- 2.18 vs 180.4 +/- 8.7 and 7.75, P < 0.05) at 8.8 m.s-1. After 4-min trials at 9.2 m.s-1, HR deltas were 6 bpm, lactate values were 9.00 +/- 1.84 and 5.22 +/- 1.18 for unaided and drafting, respectively. Sprint performance was better following drafting (33.46 +/- 1.19 vs 34.03 s, P < 0.05). HR and LA deltas during the 8.8 m.s-1 trials ranged from 0.8 to 12.4 and -0.18 to 5.37, respectively, indicating that some skaters were more effective drafters than others. These results suggest that drafting could be an important strategy in short-track speed skating, and drafting technique should be emphasized in training.

Effect of fatigue on maximal velocity and maximal torque during short exhausting cycling

A group of 24 subjects performed on a cycle ergometer a fatigue test consisting of four successive all-out sprints against the same braking torque. The subjects were not allowed time to recover between sprints and consequently the test duration was shorter than 30 s. The pedal velocity was recorded every 10 ms from a disc fixed to the flywheel with 360 slots passing in front of a photo-electric cell linked to a microcomputer which processed the data. Taking into account the variation of kinetic energy of the ergometer flywheel, it was possible to determine the linear torque velocity relationship from data obtained during the all-out cycling exercise by computing torque and velocity from zero velocity to peak velocity according to a method proposed previously. The maximal theoretical velocity (v(0)) and the maximal theoretical torque (T(0)) were estimated by extrapolation of each torque-velocity relationship. Maximal power (P(max)) was calculated from the values of T(0) and v(0) (P(max) = 0.25v(0)T(0). The kinetics of v(0), T(0) and P(max) was assumed to express the effects of fatigue on the muscle contractile properties (maximal shortening velocity, maximal muscle strength and maximal power). Fatigue induced a parallel shift to the left of the torque-velocity relationships. The v( 0), T(0) and P(max) decreases were equal to 16.3 percent, 17.3 percent and 31 percent, respectively. The magnitude of the decrease was similar for v(0) and T(0) which suggested that P max decreased because of a slowing of maximal shortening velocity as well as a loss in maximal muscle strength. However, the interpretation of a decrease in cycling v(0) which has the dimension of a maximal cycling frequency is made difficult by the possible interactions between the agonistic and the antagonistic muscles and could also be explained by a slowing of the muscle relaxation rate.

Relationship between gear ratio and 10-s sprint cycling on an air-braked ergometer

This investigation examined the relationship between gear ratio and peak and mean power outputs (PPO and MPO) and peak cadence (PC) during a 10-s all-out sprint on a multi-geared air-braked cycle ergometer. Ten physically active men [mean age 21.0 years (SEM 0.7)] performed in random order six 10-s sprints (15-min rest between each sprint) on two occasions (48 h apart) in six different gear ratios; flywheel revolutions per pedal crank revolution (FR/PCR) ranged between 5.22 and 11.61. The PPO, MPO, and PC were recorded from each sprint. Of the six gear ratios tested, a gear ratio eliciting 8.87 FR/PCR elicited the highest PPO for the initial test session; the PPO output of 1274 W was significantly greater (P < 0.01) than that produced in the other five gears. Analysis of data from the second test session revealed no statistically significant difference in PPO between gear ratios eliciting 8.00, 8.87, and 10.06 FR/PCR. The PPO from these three ratios were significantly greater (P < 0.05) than those produced using the ratios resulting in 6.32, 7.06, and 10.78 FR/PCR. The PC in the gear ratio maximising PPO was 120 rpm. Analysis of PC data revealed a significant decrease (P < 0.05) as the number of FR/PCR increased.