ECSS Paris 2023: OP-AP43
INTRODUCTION: The anaerobic metabolism contributes 10 to 50% of total energy demand during endurance exercise of 8 to 2 min and is understood well on a cellular level.(1,2) Nonetheless, its role for endurance performance is a matter of debate. Uncertainty concerning valid measurement of anaerobic capacity and power (3,4) could be a confounding factor for addressing this debate. Hence, purpose of this study was to collect 13 different metrics of anaerobic capacity and power, test within-variable relationships and assess explained variance for 3- and 12-min running performance. METHODS: 40 trained male and female runners completed three test days. The first two days incorporated a 3- and 12-min time trial (TT) to assess running performance, critical speed (CS) and finite distance capacity (D’). Additionally, participants completed a 100-m sprint (v100, MSS, cLamax, ASR, SRR) and jump test (CMJ). The third day consisted of an incremental test to exhaustion and a 4-min TT one hour thereafter. Gas exchange was recorded to assess maximal aerobic speed (MAS), VO2max, running economy, and maximal accumulated oxygen deficit (MAOD, %ANAER). Maximal post-test lactate concentration was measured for all exhaustive tests (LaRT, LaTT3, LaTT4, LaTT12). Interaction between anaerobic variables and explained variance of TT performance was tested through (multiple) regression analysis. RESULTS: Metrics of anaerobic power (v100, MSS, CMJ, cLamax) displayed high interrelationships (r=0.76-0.98, p<0.001). Anaerobic capacity metrics were interrelated to a moderate extent in the case of MAOD, %ANAER, D’ and LaTT3 (r=0.34-0.66, p<0.05), but LaRT, LaTT4, LaTT12 showed weak or absent relationships with MAOD, %ANAER and D’ (r<0.47). Anaerobic power explained 15- 51% of the variance for 3-min and up to 19% for 12-min TT performance. Capacity metrics (MAOD, %ANAER, D’) 13- 36% and 1- 13% for 3- and 12-min TT, respectively. No variance in TT could be explained by post-exhaustive lactate measures. Multiple regression models increased explained variance to 86% and 89% for 3- and 12-min TT. VO2max explained greatest variance for both TTs, and anaerobic metrics (MAOD, D’) contributed to higher explained variance for 3-min TT but failed to do so for 12-min TT. CONCLUSION: Amongst trained runners, both anaerobic power and capacity seem to be relevant for short but not longer duration endurance running. This is in line with previous work, which suggests high energy contribution from anaerobic pathways in short endurance exercise.(1) Absent relationships of post-exhaustion lactate and endurance performance may be attributed to the measurement of a net concentration, which can be influenced by various factors.(2) In accordance with previous articles,(3) we recommend caution with post-exhaustion lactate when testing trained runners. MSS, CMJ, MAOD and D’ can be viable alternatives based on our results. 1) Gastin (2001) Sports Med 2) Robergs et al. (2004) Sports Med 3) Green & Dawson (1993) Sports Med 4) Noordhof et al. (2013) IJSPP
Read CV Yannick SondermannECSS Paris 2023: OP-AP43
INTRODUCTION: Physiological models of marathon performance typically consider the maximal oxygen consumption (V̇O2max), the fraction of V̇O2max that can be sustained (V̇O2 at lactate threshold [V̇O2LT]), and running economy (RE) [1]. However, these parameters deteriorate during or after prolonged exercise [2]. The resilience to this deterioration has been termed ‘durability’ and exhibits considerable heterogeneity [3] but has not been studied extensively in running. Furthermore, it is unclear whether parameters that are typically measured in a rested state, when measured after a prolonged bout of running, can be used to predict marathon performance. The aims of this study were to examine: i) changes to physiological parameters associated with marathon performance following prolonged exercise, ii) the association of fresh and fatigued physiological parameters with marathon performance, and iii) whether marathon performance (i.e., average running speed during the marathon) could be better predicted using physiological parameters measured after prolonged exercise. METHODS: Eighteen runners (11 males, age: 41±12 yrs, marathon finish time: 197.5±32.5 min) participating in the 2024 London Marathon underwent two incremental exercise tests to measure V̇O2peak, V̇O2LT, and RE. Tests were conducted in a fresh state (FRE), and in a fatigued state, after a 90-minute run at LT (FAT). Paired samples t-test was used to test for differences in V̇O2LT, V̇O2peak, and RE between FRE and FAT. To investigate the relationship between laboratory-derived measures in both FRE and FAT, as well as the percentage change from FRE to FAT, and marathon performance, Pearson product-moment correlation coefficient was used. Significance was set at P<0.05. A linear regression analysis assessed if V̇O2LT and RE measured in FAT and FRE conditions could be used to predict marathon performance. RESULTS: Reductions in V̇O2peak (FRE: 56.7±7.2 ml·kg-1·min-1 vs. FAT: 53.4±6.3 ml·kg-1·min-1) and V̇O2 at LT (RE: 43.4±6.0 ml·kg-1·min-1 vs. FAT: 40.7±6.5 ml·kg-1·min-1) were evident (both P<0.001), but RE remained unchanged (P=0.125). Marathon performance was strongly correlated with FRE V̇O2peak (r=0.809), V̇O2LT (r=0.693), and RE (r=-0.481), as well as FAT V̇O2peak (r=0.812), V̇O2LT (r=0.781), and RE (r=-0.628) (all P<0.01). The percentage change in V̇O2LT between FRE and FAT was associated with marathon performance (r=0.543, P<0.05). Marathon performance was strongly predicted by combining V̇O2LT and RE from both FRE (R2=0.883) and FAT (R2 0.933) conditions (both P< 0.001). CONCLUSION: Prolonged running impairs key physiological parameters associated with endurance performance, and the degree of this deterioration, i.e., durability, is associated with, and helps explain marathon performance. Marathon runners and coaches should consider quantifying durability for accurate predictions of performance and talent identification. [1] Joyner & Coyle (2008) [2] Jones (2024) [3] Maunder et al. (2021)
Read CV Ben HunterECSS Paris 2023: OP-AP43
INTRODUCTION: Participation in an ultra-endurance event is associated with the development of neuromuscular fatigue (i.e., force loss) due to suboptimal drive from the central nervous system as well as impaired muscle contractile function. This study aimed to quantify, in females, both central and peripheral mechanisms of fatigue in the muscles that lift the toes (i.e., the dorsiflexors) following a multi-stage ultramarathon. METHODS: Ten females (26-47 years; 1.57-1.82 m; 49.3-132.6 kg), with diverse running experience and athletic backgrounds, participated in a 6-day ultramarathon staged around a 2.5-mile loop in La Quinta, California. Athletes completed neuromuscular testing 2-4 days prior to, and 24 hours following the event. A custom-built isometric ankle myograph was used to measure maximal voluntary as well as electrically-evoked torques of the dorsiflexors. Electrically-evoked responses were obtained by stimulating the common fibular nerve via a hand-held bar electrode. A single stimulus was delivered during the plateau phase of maximal voluntary contractions (MVCs) and ~1 second post-MVC in order to quantify levels of neural drive (i.e., voluntary activation; VA). To indirectly assess peripheral fatigue and temporary muscle damage, torque responses were recorded after a single pulse (i.e., the resting twitch; RT) as well as 1-second trains of low- and high-frequency stimulation (10 and 100 Hz, respectively). RESULTS: By the end of the event, a range of 112.2-560.3 miles had been run by the athletes. Mean MVC torque as well as VA were not different between pre- and post-event measures (32.8±8.0 vs. 29.5±6.9 Nm and 99.8±0.5 vs 98.6±2.6%, respectively; P≥0.117). Peak torque and the peak rate of torque relaxation of the RT increased by ~14.5 and 14.8%, respectively from baseline following the event (P≤0.020). Peak torque of the 10-Hz tetanus increased by 19.1% (P=0.023), but the 100-Hz response was not different (P=0.540). The ratio of 10:100 Hz torque was also not different from baseline to 24 hours post-event (0.50±0.18 vs 0.53±0.11; P=0.340). CONCLUSION: In conclusion, despite the long distances achieved among the athletes, there was no evidence of muscle damage or impairments to voluntary muscle strength and neural drive 24 hours following the 6-day ultramarathon. Our findings contribute to the growing narrative that females exhibit exceptional resistance to peripheral fatigue following ultra-endurance events.
Read CV Christina D. BruceECSS Paris 2023: OP-AP43