Post-exercise lactate recovery kinetics during growth remain poorly characterized, particularly in girls, limiting understanding of how age interacts with sex-specific metabolic adaptations. This study examined age- and sex-related differences in blood lactate recovery following high-intensity exercise from childhood to adolescence, focusing on lactate exchange (γ₁) and removal (γ₂) capacities. Seventy-six trained participants (41 boys, 35 girls) aged 10–17 years completed a 60 s all-out rowing test. Participants were stratified into four age groups: 10.0–11.9, 12.0–13.9, 14.0–15.9, and 16.0–17.9 years. Blood lactate concentrations were monitored over a 60-min passive recovery period and analyzed using the biexponential Freund model to estimate γ₁ and γ₂. End-exercise ([La]end) and peak ([La]max) lactate concentrations were measured, and absolute lactate quantities were calculated relative to lean body mass (QLaend, QLamax). Blood lactate concentrations and quantities increased with age, with boys showing higher QLaend and QLamax from 14 years onward (p < 0.001), likely reflecting greater lean mass and power output. Both γ₁ and γ₂ declined significantly with age (from 16 and 14 years, respectively; p < 0.05), indicating reduced lactate handling capacities. Girls consistently exhibited higher γ₁ values than boys (p < 0.001), which may indicate more favorable lactate exchange characteristics. This study provides the first detailed characterization of post-exercise lactate recovery kinetics in growing girls, offering novel insight into female-specific metabolic adaptations and their interplay with age. These developmental patterns enhance understanding of age-associated metabolic adaptations and may inform sex- and age-tailored training strategies in pediatric populations.

The aim of this study is to determine the effect of stroke rate on performance, technique and core stability during rowing ergometer. Twenty-four high-level rowers performed maximal intensity one-minute bouts at 20, 28 and 34 spm on a RowPerfect3 ergometer. Power at the handle, legs, trunk and arms levels were determined, and core kinematics and neuromuscular activations were measured. The power at the handle was enhanced with a higher stroke rate in the first half of the drive phase due to higher segment's powers. This resulted in technical changes, as for instance greater mean to peak power ratio at each segment level. The higher trunk power preceded a delayed trunk extension but without significant increase in the erector spinae activation. This underlines the role of the core stability to transfer forces at a higher stroke rate. However, no co-activation parameters between trunk flexors and extensors helped further to understand this force transfer. Rowing at low stroke rate can be a training strategy to work on earlier trunk extension, while maintaining erectors spinae levels of activation. Training at higher stroke rate will induce a rowing technique closer to competition with greater neuromuscular activations, and maximise power production.

The present study aimed to evaluate the effects of age and sex on the rating of perceived exertion (RPE) during high-intensity exercise and determine whether mechanical and physiological parameters could be predictors of RPE during childhood and adolescence. Forty-three boys and 36 girls performed a 60-s all-out test on a rowing ergometer and were categorized by age group (10.0-11.9; 12.0-13.9; 14.0-15.9; 16.0-17.9 years) and sex. Ratings of perceived exertion were assessed using the 6-20 RPE and CR-10 scales and analyzed with respect to mechanical work rate (Wtot ), post-exercise peak blood lactate concentration ([La]peak ), and peak minute ventilation (V̇Epeak ). Multilevel regression modeling revealed a significant influence of Wtot , [La]peak and V̇Epeak on 6-20 RPE and CR-10 scores (r2  = .34 and .36, p < .001, respectively). However, while boys perceived high-intensity exercise as being subjectively more difficult than girls at all ages (p < .05) except 12.0-13.9 years, significant higher mechanical work rate and greater associated metabolic responses in boys than girls were only found from the age of 14 years (Wtot and V̇Epeak ) or 16 years ([La]peak ), suggesting that the association between RPE and mechanical/physiological parameters could not be held before the age of 12 years. To conclude, RPE increased with increasing age, with boys exhibiting higher scores than girls at all ages except 12.0-13.9 years. This finding is probably explained by the higher Wtot and greater concomitant metabolic responses in boys at the time of puberty. However, other factors should be considered at least in children before the age of 12 years.

The purpose of this study was to evaluate the influence of technical and core stability parameters on rowing ergometer performance defined as mean power at the handle. Twenty-four high-level rowers were evaluated at their competitive stroke rate on an instrumented RowPerfect 3 ergometer to determine leg, trunk and arm power output, while trunk and pelvis 3D kinematics were measured. Linear mixed models revealed that mean power at the handle was predicted by the power output of legs, trunk and arms (r(2) = 0.99), with trunk power being the best predictor. Time to peak power, work ratio and mean to peak power ratio were relevant technical parameters significantly predicting the different segments' power. In addition, a greater trunk range of motion significantly influenced the power produced by this segment. Accordingly, achieving an earlier peak power together with enhanced work production at the trunk and arm levels, as well as distributing the segments power over the whole drive phase, could serve as recommendations for technical training of rowers on dynamic ergometers in order to produce higher power output. Furthermore, the trunk appears to play a major role as a power producer within the kinetic chain from the legs to the arms.

Objectives: To investigate the effect of menstrual cycle (MC) and hormonal contraception (HC) phases in elite rowers training, performance and wellness monitoring. Methods: Twelve French elite rowers were follow-up for 4,2 cycles on average in their final preparation for the Olympics and Paralympics Games in Tokyo 2021 through an on-site longitudinal study based on repeated measures. Daily self-reported evaluation using Likert rating scales of wellness (sleep quality, fitness, mood, injuries' pain), menstrual symptoms and training parameters (perceived exertion and self-assessment of performance) were collected (n = 1,281) in parallel to a coach evaluation of rowers' performance (n = 136), blinded to theirs MC and HC phases. Salivary samples of estradiol and progesterone were collected in each cycle to help to classify the MC into 6 phases and HC into 2-3 phases depending on the pills' hormone concentration. A chi-square test normalized by each rower was used to compare the upper quintile scores of each studied variable across phases. A Bayesian ordinal logistic regression was applied to model the rowers' self-reported performance. Results: Rowers with a natural cycle, n = 6 ( + 1 amenorrhea) evaluate their performance and wellness with significant higher score indices at the middle of their cycle. Top assessments are rarer at the premenstrual and menses phases, when they more frequently experience menstrual symptoms which are negatively correlated with their performance. The HC rowers, n = 5, also better evaluate their performance when taking the pills and more frequently experience menstrual symptoms during the pill withdrawal. The athletes self-reported performance is correlated with their coach's evaluation. Conclusion: It seems important to integrate MC and HC data in the wellness and training monitoring of female athletes since these parameters vary across hormonal phases affecting training perception of both athlete and coach.

French rowing federation reduced the competition distance to 1,500 and 1,000 m in rowers under 16- (U16) and 14-year-old (U14) respectively, to prepare them progressively to the Olympic 2,000 m distance in under 18-year-old (U18). This study aimed to check the hypothesis that relative aerobic (%EAe) and anaerobic (%EAn) energy contributions would be comparable between the competition distances since the more oxidative profile of younger age categories could offset the greater anaerobic contribution induced by shorter rowing races. Thirty-one 12- to 17-year-old competitive rowers performed a race of 2,000, 1,500, or 1,000 m on a rowing ergometer according to their age category. %EAe and %EAn were estimated from oxygen consumption, changes in blood lactate concentration and their energy equivalents. %EAe was lower in U16 than U18 (84.7 vs. 87.0%, p < 0.01), and in U14 than U16 (80.6 vs. 84.7%, p < 0.001). %EAn was higher in U16 than U18 (15.3 vs. 13.0%, p < 0.01), and in U14 than U16 (19.4 vs. 15.3%, p < 0.01). The results did not confirm our initial hypothesis since %EAe and %EAn were significantly different between the race distances, and thus age categories. However, %EAn in U18, U16 and U14 were found to be in the range of values previously found in adult rowers over the 2,000 m Olympic distance (12–30%). Therefore, on a practical level, the strategy implemented by the French rowing federation to reduce the competition distance in the younger age categories could be relevant to progressively prepare them to the physiological requirements encountered over the Olympic distance.

PURPOSE To determine sex-related differences in oxygen consumption (V˙O2) recovery after high-intensity exercise during childhood and adolescence. METHODS Forty-two boys and 35 girls (10-17 y) performed a 60-second all-out test on a rowing ergometer. Postexercise V˙O2 recovery was analyzed from (1) the V˙O2 recovery time constant obtained from a biexponential model (τ1V˙O2) and (2) excess postexercise oxygen consumption calculated over a period of 8 minutes (EPOC8) and until τ1V˙O2 was reached (EPOCτ1). Multiplicative allometric modeling was used to assess the concurrent effects of body mass or lean body mass, and age on EPOC8 and EPOCτ1. RESULTS EPOC8 increased significantly more in boys from the age of 14 years. However, the sex difference was no longer significant when EPOC8 was analyzed using an allometric model including body mass + age or lean body mass + age. In addition, despite a greater increase in EPOCτ1 in boys from the age of 14 years, τ1V˙O2 was not significantly different between sexes whatever age. CONCLUSION While age and lean body mass accounted for the sex-related differences of EPOC during childhood and adolescence, no significant effect of age and sex was observed on the V˙O2 recovery time constant after high-intensity exercise.

The aims of the present study were to determine during childhood and adolescence (i) the effect of sex on non-oxidative energy production, quantified by the accumulated oxygen deficit (AOD), and (ii) the influence of AOD on high-intensity performance. Thirty-nine boys and 35 girls aged 10–17 years performed a 60 s all-out test on a rowing ergometer to determine AOD and mean power output (MPO). Multiplicative allometric modelling was used to assess the concurrent effects of lean body mass (LBM) and age on AOD. AOD significantly increased with age in both sexes (p < 0.001) with boys exhibiting significantly higher AOD than girls from the age of 14 years (10–11.9 yr: 1.9 vs 1.9 L, 12–13.9 yr: 2.4 vs 2.7 L, 14–15.9 yr: 2.8 vs 4.6 L and 16–17.9 yr: 2.9 vs 5.2 L, in girls and boys respectively, p < 0.001). However, a sex difference was no longer significant when AOD was analysed using an allometric model including age and LBM (p = 0.885). Finally, significant correlations were found between AOD and MPO in boys and girls but with lower evidence in girls (r2 = 0.41 vs. 0.89). Non-oxidative energy production increased more extensively in boys than girls from the age of 14 years. Age and LBM accounted for the sexual differentiation of AOD during childhood and adolescence. In addition, AOD was found to be a determinant factor of high-intensity performance, more particularly in boys.

This study aimed to test if the non-oxidative energy supply ( estimated by the accumulated oxygen deficit) is associated with an index of muscle lactate accumulation during exercise, muscle monocarboxylate transporter content and the lactate removal ability during recovery in well-trained rowers. Seventeen rowers completed a 3-min all-out exercise on rowing ergometer to estimate the accumulated oxygen deficit. Blood lactate samples were collected during the subsequent passive recovery to assess individual blood lactate curves, which were fitted to the bi-exponential time function: La(t) = [ La](0) + A(1) . (1-e(1)(-nu t)) + A(2) . (1- e(2)(-nu t)), where the velocity constants gamma(1) and gamma(2) (min(-1)) denote the lactate exchange and removal abilities during recovery, respectively. The accumulated oxygen deficit was correlated with the net amount of lactate released from the previously active muscles (r = 0.58, P < 0.05), the monocarboxylate transporters MCT1 and MCT4 (r = 0.63, P < 0.05) and gamma(2) (r = 0.55, P < 0.05). gamma(2) and the lactate release rate at exercise completion were negatively correlated with citrate synthase activity. These findings suggest that the capacity to supply nonoxidative energy during supramaximal rowing exercise is associated with muscle lactate accumulation and transport, as well as lactate removal ability.

1 Le Mans University, Laboratory ‛Movement, Interactions, Performance’ (EA 4334), Faculty of Sciences and Technologies, Department of Sport Sciences, Le Mans, France 2 University of Paris-Est Créteil, Laboratory ‛Bioingenierie, Tissus et Neuroplasticité’ (EA 7377), Créteil, France 3 Laboratory of Biomechanics and Human Modelling, Faculty of Medicine Lyon-Sud, Oullins cedex, France 4 French Rowing Federation, Nogent-sur-Marne, France 5 Blaise-Pascal University, Laboratory AME2P, UFR STAPS, Aubière, France

The purpose of this study was to investigate whether 3 different approaches for evaluating squat jump performance were correlated with rowing ergometer performance in elite adolescent rowers. Fourteen young male competitive rowers (15.3 +/- 0.6 years), who took part in the French rowing national championships, performed a 1,500-m all-out rowing ergometer performance (P-1500) and a squat jump (SJ) test. The performance in SJ was determined by calculating the jump height (H-SJ in cm), a jump index (I-SJ = H-SJ.body mass.gravity, in J), and the mean power output (P-SJ in W) from the Samozino et al.'s method. Furthermore, allometric modeling procedures were used to consider the importance of body mass (BM) in the relationships between P-1500 and jump scores. P-1500 was significantly correlated with H-SJ (r(2) = 0.29, p <= 0.05), I-SJ (r(2) = 0.72, p, 0.0001), and P-SJ (r(2) = 0.86, p < 0.0001). Furthermore, BM explained at least 96% of the relationships between SJ and rowing performances. However, the similarity between both allometric exponents for P-SJ and P-1500 (1.15 and 1.04, respectively) indicates that BM could influence jump and rowing ergometer performances at the same rate, and that P-SJ could be the best correlate of P-1500. Therefore, the calculation of power seems to be more relevant than H-SJ and I-SJ to (a) evaluate jump performance and (b) infer the capacity of adolescent rowers to perform 1,500-m all-out rowing ergometer performance, irrespective of their body mass. This could help coaches to improve their training program and potentially identify talented young rowers.

The aim of this study was to determine whether prepubertal children are metabolically comparable to well-trained adult endurance athletes and if this translates into similar fatigue rates during high-intensity exercise in both populations. On two different occasions, 12 prepubertal boys (10.5 ± 1.1 y), 12 untrained men (21.2 ± 1.5 y), and 13 endurance male athletes (21.5 ± 2.7 y) completed an incremental test to determine the power output at VO2max (PVO2max) and a Wingate test to evaluate the maximal anaerobic power (Pmax) and relative decrement in power output (i.e., the fatigue index, FI). Furthermore, oxygen uptake (VO2), heart rate (HR), and capillary blood lactate concentration ([La]) were measured to determine (i) the net aerobic contribution at 5-s intervals during the Wingate test, and (ii) the post-exercise recovery kinetics of VO2, HR, and [La]. The Pmax-to-PVO2max ratio was not significantly different between children (1.9 ± 0.5) and endurance athletes (2.1 ± 0.2) but lower than untrained men (3.2 ± 0.3, p < 0.001 for both). The relative energy contribution derived from oxidative metabolism was also similar in children and endurance athletes but greater than untrained men over the second half of the Wingate test (p < 0.001 for both). Furthermore, the post-exercise recovery kinetics of VO2, HR, and [La] in children and endurance athletes were faster than those of untrained men. Finally, FI was comparable between children and endurance athletes (-35.2 ± 9.6 vs. -41.8 ± 9.4%, respectively) but lower than untrained men (-51.8 ± 4.1%, p < 0.01). To conclude, prepubertal children were observed to be metabolically comparable to well-trained adult endurance athletes, and were thus less fatigable during high-intensity exercise than untrained adults.

The purpose of this study was to test if the lactate exchange (γ1) and removal (γ2) abilities during recovery following short all-out supramaximal exercise correlate with the muscle content of MCT1 and MCT4, the two isoforms of the monocarboxylate transporters family involved in lactate and H+ co-transport in skeletal muscle. Eighteen lightweight rowers completed a 3-min all-out exercise on rowing ergometer. Blood lactate samples were collected during the subsequent passive recovery to assess an individual blood lactate curve (IBLC). IBLC were fitted to the bi-exponential time function: La(t) = [La](0) + A1(1 − e-γ1t) + A2(1 − e-γ2t) where [La](0) is the blood lactate concentration at exercise completion and the velocity constants γ1 and γ2 denote the lactate exchange and removal abilities, respectively. An application of the bi-compartmental model of lactate distribution space allowed estimation of the lactate removal rate at exercise completion [LRR(0)]. Biopsy of the right vastus lateralis was taken at rest to measure muscle MCT1 and MCT4 content. Fiber type distribution, activity of key enzymes and capillary density (CD) were also assessed. γ1 was correlated with [La](0) (r = −0.54, P < 0.05) but not with MCT1, MCT4 or CD. γ2 and LRR(0) were correlated with MCT4 (r = 0.63, P < 0.01 and r = 0.73, P < 0.001, respectively) but not with MCT1 or cytochrome c oxidase activity. These findings suggest that the lactate exchange ability is highly dependent on the milieu so that the importance of the muscle MCT1 and MCT4 content in γ1 was hidden in the present study. Our results also suggest that during recovery following all-out supramaximal exercise in well-trained rowers, MCT4 might play a significant role in the distribution and delivery of lactate for its subsequent removal.

This study aimed at testing the possible correlation between rowers’ ability to generate power during a rowing Wingate test or a squat jump test and a rowing ergometer performance. Mean power developped during the Wingate test (PWIN), force, velocity and power output in squat jump (FSJ, VSJ and PSJ) and mean power (P1500) sustained during an all-out 1500-m sprint ergometer were measured in fourteen young rowers (15.3±0.6 yr, 178.5±8.8 cm, 67.9±10.8 kg). PWIN was significantly correlated to P1500 (r=0.90, P<0.001). FSJ, VSJ and PSJ were also significantly correlated to P1500 (r=0.54-0.87, P<0.001). Rowers presenting the highest power capacities, in either Wingate or squat jump test, were also the ones showing the best performances. In young rowers, the power capacity highlighted by Wingate and squat jump tests, are determinants for success in rowing performance.

PURPOSEThe aim of the current study was to determine whether the anaerobic performance assessed by a modified Wingate test could account for the 1,500-m rowing ergometer performance in young competitive rowers.METHODSFourteen national-level adolescent rowers performed on a rowing ergometer i) a 30-s allout exercise (i.e., modified Wingate test) and ii) a 1,500-m all-out exercise (i.e., rowing performance). For each of these two exercises, the mean power output was considered as the main performance criterion (PWIN and P1500, respectively).RESULTSPWIN was correlated to P1500 (r2 = .83, p < .0001, β = 100%). Furthermore, the estimated total muscle mass was correlated to PWIN and P1500 (r2 = .72 and r2 = .83, p < .0001, β = 100%, respectively). The allometric scaling also indicated that total muscle mass accounts 62% for the relationship between PWIN and P1500.CONCLUSIONOur results highlight the importance of considering the contribution of total muscle mass and anaerobic energy pathways to 1,500-m rowing performance in competitive adolescent rowers. Therefore, the modified Wingate test could be used by rowing coaches to potentially identify talented young rowers.