Exercise tolerance during VO2maxtesting is a multifactorial psychobiological phenomenon

Clustering analysis across different speeds reveals two distinct running techniques with no differences in running economy

Establishing the links between running technique and economy remains elusive due to high inter-individual variability. Clustering runners by technique may enable tailored training recommendations, yet it is unclear if different techniques are equally economical and whether clusters are speed-dependent. This study aimed to identify clusters of runners based on technique and to compare cluster kinematics and running economy. Additionally, we examined the agreement of clustering partitions of the same runners at different speeds. Trunk and lower-body kinematics were captured from 84 trained runners at different speeds on a treadmill. We used Principal Component Analysis for dimensionality reduction and agglomerative hierarchical clustering to identify groups of runners with a similar technique, and we evaluated cluster agreement across speeds. Clustering runners at different speeds independently produced different partitions, suggesting single speed clustering can fail to capture the full speed profile of a runner. The two clusters identified using data from the whole range of speeds showed differences in pelvis tilt and duty factor. In agreement with self-optimisation theories, there were no differences in running economy, and no differences in participants' characteristics between clusters. Considering inter-individual technique variability may enhance the efficacy of training designs as opposed to 'one size fits all' approaches.

Maximal and Submaximal Cardiorespiratory Responses to a Novel Graded Karate Test

The present study aimed to propose and assess the physiological responses of a novel graded karate test. Ten male national-level karate athletes (age 26 ± 5 yrs; body mass 69.5 ± 11.6 kg; height 1.70 ± 0.09 m) performed two exercise tests (separated by 2-7 days): 1) a running-based cardiopulmonary exercise test; 2) a graded karate test. The cardiopulmonary exercise test was comprised of an individualized ramp protocol for treadmill running, and the graded karate test was comprised of a sequence of 'kisami-gyaku-zuki" punching at a fixed frequency of a stationary target that becomes progressively distant. Cardiorespiratory responses, blood lactate concentration, and perceived exertion were measured. A verification phase was also performed in both tests to confirm the maximal physiological outcomes. The graded karate test evoked similar maximal responses to the running protocol: V̇O₂ (57.4 ± 5.1 vs 58.3 ± 3.5 mL·kg^-1·min^-1; p = 0.53), heart rate (192 ± 6 vs 193 ± 10]beats.min^-1; p = 0.62) and blood lactate (14.6 ± 3.4 vs 13.1 ± 3.0 mmol·L^-1; p = 0.14) with a shorter duration (351 ± 71 vs 640 ± 9 s; p < 0.001). Additionally, the graded karate test evoked higher V̇O₂ (72.6 ± 6.5 vs 64.4 ± 4.3 %V̇O_2MAX; p = 0.005) and heart rate (89.4 ± 4.6 vs 77.3 ± 7.2 %HR_MAX p < 0.001) at the ventilatory threshold and a higher heart rate (97.0 ± 2.4 vs 92.9 ± 2.2 %HR_MAX; p = 0.02) at the respiratory compensation point. Incremental and verification phases evoked similar responses in V̇O₂ and minute-ventilation during both tests. This novel displacement-based sport-specific test evoked similar maximal and higher submaximal responses, indicating a superior pathway to assess karate athletes.

Two weeks of lower body resistance training enhances cycling tolerability to improve precision of maximal cardiopulmonary exercise testing in sedentary middle-aged females

It is not uncommon for sedentary individuals to cite leg fatigue as the primary factor for test termination during a cardiopulmonary exercise test (CPET) on a cycle ergometer. The purpose of this study was to examine the effect of 2 weeks of lower body resistance training (RT) on cardiopulmonary capacity in sedentary middle-aged females. Additionally, the impact of RT on muscle strength was evaluated. Following familiarization, 28 women (18 exercise group, 10 control group) completed a maximal CPET on a cycle ergometer to determine peak oxygen uptake and leg extensor strength assessed using isokinetic dynamometry. Participants in the exercise group performed 2 weeks (6 sessions) of lower body RT, which comprised leg press, leg curl, and leg extension exercises. A 2-way repeated-measures ANOVA was used to evaluate the difference in changes of peak oxygen uptake and peak torque (PT). Peak oxygen uptake significantly improved from 22.2 ± 4.5 mL·kg^-1·min^-1 to 24.3 ± 4.4 mL·kg^-1·min^-1 (10.8%, p < 0.05) as well as PT from 83.1 ± 25.4 Nm to 89.0 ± 29.7 Nm (6.1%, p < 0.05) in the exercise group with no change in the control group. These findings provide initial evidence that 2 weeks of lower body RT prior to a CPET may be a helpful preconditioning strategy to achieve a more accurate peak oxygen uptake during testing, enhancing tolerability to a CPET by improving lower body strength.

Effect of ramp slope on different methods to determine lactate threshold in semi-professional soccer players

The present study aimed to investigate the effect of stage duration in incremental protocols on lactate threshold (LT), determined by different methods. Sixteen semi-professional soccer-players performed a 4-min stage incremental discontinuous (DP) and two maximal incremental running continuous (1 km h^-1· min^-1, CP1; and 1 km h^-1·2 min^-1 CP2) protocols. Blood-lactate concentration [La^-] was measured at baseline and during the protocols. LT was determined using D_MAX, D_MAX-MOD, 4-mM⋅L^-1, Δ1-mM⋅L^-1 and Log-Log methods. Log-Log showed no difference in LT between CP1, CP2 and DP. Conversely, LT was determined at higher velocity in CP1 than CP2 for D_MAX (15.2 ± 0.5 vs 14.4 ± 1.2 km⋅h^-1, P = 0.002), D_MAX-MOD (16.0 ± 0.5 vs 14.7 ± 1.3 km⋅h^-1, P < 0.001), 4-mM⋅L^-1 (15.5 ± 1.4 vs 14.4 ± 1.2 km⋅h^-1, P < 0.001), Δ1-mM⋅L^-1 (15.5 ± 1.3 vs 14.4 ± 1.2 km⋅h^-1, P < 0.001). Higher LT in CP1 than DP for D_MAX (15.2 ± 0.5 vs 13.0 ± 1.0 km⋅h^-1, P < 0.001) and D_MAX-MOD (16.0 ± 0.5 vs 13.6 ± 1.6 km⋅h^-1, P < 0.001) was found (P < 0.001). Log-Log resulted in shorter but accurate protocols to determine LT.