Metabolic and cardioventilatory responses during a graded exercise test before and 24 h after a triathlon

The Impact of Exercise-Induced Muscle Damage on Various Cycling Performance Metrics: A Systematic Review and Meta-Analysis

ABSTRACT

Devantier-Thomas, B, Deakin, GB, Crowther, F, Schumann, M, and Doma, K. The impact of exercise-induced muscle damage on various cycling performance metrics: a systematic review and meta-analysis. J Strength Cond Res 38(8): 1509-1525, 2024-This systematic review and meta-analysis examined the impact of exercise-induced muscle damage (EIMD) on cycling performance. The primary outcome measure was cycling performance, whereas secondary outcome measures included creatine kinase (CK), delayed-onset muscle soreness (DOMS), and muscular contractions. Data were extracted and quantified through forest plots to report on the standardized mean difference and p values. The meta-analysis showed no significant change in oxygen consumption at 24-48 hours ( p > 0.05) after the muscle damage protocol, although ventilation and rating of perceived exertion significantly increased ( p < 0.05) during submaximal cycling protocols. Peak power output during both sprint and incremental cycling performance was significantly reduced ( p < 0.05), but time-trial and distance-trial performance showed no change ( p > 0.05). Measures of CK and DOMS were significantly increased ( p < 0.05), whereas muscular force was significantly reduced following the muscle-damaging protocols ( p < 0.05), confirming that cycling performance was assessed during periods of EIMD. This systematic review showed that EIMD affected both maximal and submaximal cycling performance. Therefore, coaches should consider the effect of EIMD on cycling performance when implementing unaccustomed exercise into a cycling program. Careful consideration should be taken to ensure that additional training does not impair performance and endurance adaptation.

Exercise Intensity during Olympic-Distance Triathlon in Well-Trained Age-Group Athletes: An Observational Study

The aim of this study was to examine the exercise intensity during the swimming, cycling, and running legs of nondraft legal, Olympic-distance triathlons in well-trained, age-group triathletes. Seventeen male triathletes completed incremental swimming, cycling, and running tests to exhaustion. Heart rate (HR) and workload corresponding to aerobic and anaerobic thresholds, maximal workloads, and maximal HR (HR_max) in each exercise mode were analyzed. HR and workload were monitored throughout the race. The intensity distributions in three HR zones for each discipline and five workload zones in cycling and running were quantified. The subjects were then assigned to a fast or slow group based on the total race time (range, 2 h 07 min–2 h 41 min). The mean percentages of HR_max in the swimming, cycling, and running legs were 89.8% ± 3.7%, 91.1% ± 4.4%, and 90.7% ± 5.1%, respectively, for all participants. The mean percentage of HR_max and intensity distributions during the swimming and cycling legs were similar between groups. In the running leg, the faster group spent relatively more time above HR at anaerobic threshold (AnT) and between workload at AnT and maximal workload. In conclusion, well-trained male triathletes performed at very high intensity throughout a nondraft legal, Olympic-distance triathlon race, and sustaining higher intensity during running might play a role in the success of these athletes.

A Reduction in Maximal Incremental Exercise Test Duration 48 h Post Downhill Run Is Associated with Muscle Damage Derived Exercise Induced Pain

Purpose: To examine whether exercise induced muscle damage (EIMD) and muscle soreness reduce treadmill maximal incremental exercise (MIE) test duration, and true maximal physiological performance as a consequence of exercise induced pain (EIP) and perceived effort.

Methods: Fifty (14 female), apparently healthy participants randomly allocated into a control group (CON, n = 10), or experimental group (EXP, n = 40) visited the laboratory a total of six times: visit 1 (familiarization), visit 2 (pre 1), visit 3 (pre 2), visit 4 (intervention), visit 5 (24 h post) and visit 6 (48 h post). Both groups performed identical testing during all visits, except during visit 4, where only EXP performed a 30 min downhill run and CON performed no exercise. During visits 2, 3, and 6 all participants performed MIE, and the following measurements were obtained: time to exhaustion (TTE), EIP, maximal oxygen consumption (V·O2max), rate of perceived exertion (RPE), maximum heart rate (HR_max), maximum blood lactate (BLa_max), and the contribution of pain to terminating the MIE (assessed using a questionnaire). Additionally during visits 1, 2, 3, 5, and 6 the following markers of EIMD were obtained: muscle soreness, maximum voluntary contraction (MVC), voluntary activation (VA), creatine kinase (CK).

Results: There were no significant differences (p ≥ 0.32) between any trials for any of the measures obtained during MIE for CON. In EXP, TTE decreased by 34 s (3%), from pre 2 to 48 h post (p < 0.001). There was a significant association between group (EXP, CON) and termination of the MIE due to “pain” during 48 h post (χ² = 14.7, p = 0.002).

Conclusion: EIMD resulted in premature termination of a MIE test (decreased TTE), which was associated with EIP, MVC, and VA. The exact mechanisms responsible for this require further investigation.

Metabolic and ventilatory effects of oral glucose load at rest and during incremental aerobic muscular work in young healthy adults

We measured respiratory ratio (RR), pulmonary ventilation (VE) and end-tidal carbon dioxide partial pressure (ETPCO2) at rest and during cycling aerobic workloads (20%, 40%, 60% of estimated maximal oxygen uptake). Measurements were taken after overnight fasting and after an oral glucose load. RR, VE and ETPCO2 increased with workload. Glucose load caused RR and VE increments at rest (0.75 ± 0.01 vs. 0.86 ± 0.02, p < 0.01, and 10.8 ± 0.43 vs. 12.1 ± 0.49 l/min, p < 0.01, respectively) and for each workload (20% estimated maximal oxygen uptake: 0.77 ± 0.01 vs. 0.855 ± 0.02, p < 0.01, and 16.2 ± 0.73 vs. 17.7 ± 0.8 l/min, p < 0.01; 40% estimated maximal oxygen uptake: 0.76 ± 0.02 vs. 0.82 ± 0.01, p < 0.01, and 25.9 ± 1.1 vs. 28.3 ± 1.3 l/min, p < 0.05; 60% estimated maximal oxygen uptake: 0.85 ± 0.02 vs. 0.91 ± 0.02, p < 0.01, and 37.4 ± 1.7 vs. 40.9 ± 1.9 l/min, p < 0.05) but ETPCO2 did not change. The differences in RR before and after glucose load became smaller as the workload increased. Linear regression analysis of VE and carbon dioxide output yielded virtually identical results for both fasting and glucose load conditions. We have concluded that: a) for the metabolic carbon dioxide load increment due to glucose-induced RR increment, the physiological response is an increase of VE at all workloads. This response modulates constant ETPCO2 values; b) on workload increment, skeletal muscle increasingly utilises more and more glycogen stores, regardless of the blood glucose availability. This reduces the usefulness of dietary manipulations decreasing carbon dioxide metabolic load during muscular work in respiratory failure; c) the absolute value of metabolic carbon dioxide load exerts a role in ventilation regulation at rest and during aerobic exercise.

Exercise intensity during repeated days of racing in professional triathletes

The purpose of this study was to estimate the exercise intensity from the competition heart rate (HR) of professional triathletes during a multi-triathlon race. Five internationally ranked professional triathletes completed incremental cycling and running tests to assess the first and second ventilatory thresholds (i.e., VT and RCT) and the HR at VT and RCT. HR was then monitored during a 5 d multi-triathlon race: a prologue time trial (PTT, 0.2 km swim -- 5 km cycle -- 1.2 km run) that opened the race; short-distance triathlons (SHD; 1.3 km swim -- 36 km cycle -- 8.4 km run) performed on the 2nd and 5th days; and sprint-distance triathlons (SPD; 0.75 km swim -- 20 km cycle -- 5 km run) performed on the 3rd and 4th days. All trials except the last (i.e., the second SHD) were performed above HR corresponding to RCT. PTT elicited significantly higher mean HR than the other trials (except for the first SPD trial). In contrast, the last SHD elicited significantly lower HR than the other trials. These responses were globally similar in the 3 segments (i.e., swim, cycle, and run). This study demonstrates that the triathletes performed at very high intensity during a drafting-permitted multi-triathlon race. However, as shown for multi-day cycling distances, the HR responses depended on (i) the distance covered and (ii) group behavior.