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Purpose: Fran is one of the most popular CrossFit benchmark workouts used to control CrossFitters’ improvements. Detailed physiological characterization of Fran is needed for a more specific evaluation of CrossFitters’ training performance improvements. The aim of the study was to analyze the oxygen uptake ( $\dot{\mathrm{V}}{\mathrm{O}}_2$ ) kinetics and characterize the energy system contributions and the degree of postexercise fatigue of the unbroken Fran. Methods: Twenty trained CrossFitters performed Fran at maximal exertion. $\dot{\mathrm{V}}{\mathrm{O}}_2$ and heart-rate kinetics were assessed at baseline and during and post-Fran. Blood lactate and glucose concentrations and muscular fatigue were measured at baseline and in the recovery period. Results: A marked increase in $\dot{\mathrm{V}}{\mathrm{O}}_2$ kinetics was observed at the beginning of Fran, remaining elevated until the end ( $\dot{\mathrm{V}}{\mathrm{O}}_2\mathrm{peak}$ : 49.2 [3.7] mL·kg⁻¹·min⁻¹, $\dot{\mathrm{V}}{\mathrm{O}}_2$ amplitude: 35.8 [5.2] mL·kg⁻¹·min⁻¹, time delay: 4.7 [2.5] s and time constant: 23.7 [11.1] s; mean [SD]). Aerobic, anaerobic lactic, and alactic pathways accounted for 62% (4%), 26% (4%), and 12% (2%) of energy contribution. Reduction in muscle function in jumping ability (jump height: 8% [6%], peak force: 6% [4%], and maximum velocity: 4% [2%]) and plank prone test (46% [20%]) was observed in the recovery period. Conclusions: The Fran unbroken workout is a high-intensity effort associated with an elevated metabolic response. This pattern of energy response highlights the primary contribution of aerobic energy metabolism, even during short and very intense CrossFit workouts, and that recovery can take >24 hours due to cumulative fatigue.

Purpose: Open-water swimmers need to train with wetsuits to get familiar with them; however, body core temperature (T _core) kinetics when using wetsuits in swimming-pool training remains unclear. The present study assessed the effects of wetsuit use in pool training on T _core, subjective perceptions, and swimming performance to obtain suggestions for wearing wetsuits in training situations. Methods: Four elite/international-level Japanese swimmers (2 female, age 24 [1] y) completed two 10-km trials with (WS) and without wetsuit (SS) in the swimming pool (T _w: 29.0 °C). During the trial, swimmers were allowed to remove their wetsuit if they could no longer tolerate the heat. T _core was continuously recorded via ingestible temperature sensors. Swimming speed was estimated from every 100-m lap time. Results: T _core increased by distance in both trials in all swimmers. T _core when swimmers removed their wetsuit in the WS (distance: 3800 [245] m, time: 2744 [247] s) was higher than that at the same distance in the SS in all swimmers. Rating of perceived exertion was higher in the SS than the WS, and swimming speed was slower in the WS than the SS in all swimmers. Conclusion: Wetsuit use during pool training increases T _core and decreases swimming performance. Although wearing wetsuits in training situations is important for familiarization, for the safety of the swimmers, it is recommended that they remove their wetsuit if they feel too hot.

Purpose: This study aimed to investigate acute psychophysiological responses to repeated-sprint training in hypoxia (RSH) combined with whole-body cryotherapy (WBC). Method: Sixteen trained cyclists performed 3 sessions in randomized order: RSH, WBC-RSH (WBC pre-RSH), and RSH-WBC (WBC post-RSH). RSH consisted of 3 sets of 5 × 10-second sprints with 20-second recovery at a simulated altitude of 3000 m. Power output, muscle oxygenation (tissue saturation index), heart-rate variability, and recovery perception were analyzed. Sleep quality was assessed on the nights following test sessions and compared with a control night using nocturnal ActiGraphy and heart-rate variability. Results: Power output did not differ between the conditions (P = .27), while the decrease in tissue saturation index was reduced for WBC-RSH compared to RSH-WBC in the last set. In both conditions with WBC, the recovery perception was higher compared to RSH (WBC-RSH: +15.4%, and RSH-WBC: +21.9%, P < .05). The number of movements during the RSH-WBC night was significantly lower than for the control night (−18.7%, P < .01) and WBC-RSH (−14.9%, P < .05). RSH led to a higher root mean square of the successive differences of R-R intervals and high-frequency band during the first hour of sleep compared to the control night (P < .05) and RSH-WBC (P < .01). Conclusions: Inclusion of WBC in an RSH session did not modify the power output but could improve prolonged performance in hypoxia by maintaining muscle oxygenation. A single RSH session did not deteriorate sleep quality. WBC, particularly when performed after RSH, positively influenced recovery perception and sleep.

Purpose: Rugby union is a contact team sport demanding high levels of physical capacity, and understanding the match workloads can be useful to inform training. In this study, the factors influencing locomotion and contact workloads for offensive and defensive ball-in-play periods are quantified. Methods: Locomotion and contact metrics were collected from global positioning system units and videos for 31 professional players of a Super Rugby team across 14 games in the 2021 season. Data were analyzed with a generalized mixed-model procedure that included effects for type of play, playing position, match outcome, and ball-in-play time. Magnitudes were assessed with standardization, and evidence for substantial magnitudes was derived from sampling uncertainty. Results: When offense was compared to defense, most metrics showed decisively substantial increases (small to moderate) for forwards and backs. There was decisive evidence that locomotion metrics were substantially lower (large differences) and contact metrics were higher (very large differences) when comparing forwards to backs on offense and defense. When winning was compared to losing, there was good evidence that forwards experienced small increases in overall workload on defense, and backs experienced a small increase in high-speed running and a moderate decrease in contacts on offense. Match-to-match changes associated with ball-in-play time, attributed to fatigue, were decisive (moderate to very large) across most metrics for forwards and backs in offense and defense. Conclusions: The increased locomotion and contact workloads in offensive periods and the differing physical requirements between positions and match outcomes for both types of play are novel findings that should aid practitioners in designing effective training.

Purpose: To examine the effects of 4 programming models (linear [LP], undulating [UP], reverse [RP], and constant [CP]) on physical performance. Methods: Forty-eight moderately strength-trained men were randomly assigned to LP, UP, RP, and CP groups according to their 1-repetition maximum (1RM) in the full-squat exercise (SQ) and followed an 8-week training intervention using the SQ and monitoring movement velocity for every repetition. All groups trained with similar mean relative intensity (65% 1RM), number of repetitions (240), sets (3), and interset recovery (4 min) throughout the training program. Pretraining and posttraining measurements included, in the SQ, 1RM load, the average velocity attained for all absolute loads common to pretests and posttests (AV), and the average velocity for loads that were moved faster (AV > 1) and slower (AV < 1) than 1 m·s⁻¹ at pretraining tests. Moreover, countermovement jump height and 20-m running sprint time were measured. Results: A significant time effect was found for all variables analyzed (P < .05), except for 20-m running sprint time. Significant group × time interactions were observed for 1RM, AV > 1, and AV (P < .05). After training, all groups attained significant strength gains on 1RM, AV, AV > 1, and AV < 1 (P < .001–.01). LP and RP groups improved their countermovement jump height (P < .01), but no significant changes were observed for UP and CP. No significant improvements were achieved in 20-m running sprint time for any groups. Conclusions: These different programming models are all suitable for improving physical performance. LP and RP induce similar or greater gains in physical performance than UP and CP.

Purpose : This study compared the effects of individualizing supramaximal interval rowing interventions using anaerobic power reserve (APR [high-intensity interval training (HIIT) prescribed according to individual APR (HIIT_APR)]) and power associated with maximal oxygen uptake ( ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ [HIIT prescribed based on the individual ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ (HIIT_W)]) on the homogeneity of physiological and performance adaptations. Methods : Twenty-four well-trained rowers (age 24.8 [4.3] y, stature 182.5 [3] cm, body mass 86.1 [4.3]) were randomized into interventions consisting of 4 × 30-second intervals at 130%APR ( ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ + 0.3 × maximal sprint power) with weekly progression by increasing the number of repetitions per set (5, 6, 7, 8, 9, and 10, from first to sixth session) and the same sets and repetitions with the intensity described as 130% ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ . The work-to-recovery ratio was 1:1 for repetitions and 3 minutes between sets. Responses of aerobic fitness indices, power output, cardiac hemodynamics, locomotor abilities, and time-trial performance were examined. Results : Both HIIT_APR and HIIT_W interventions significantly improved ${\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ , lactate threshold, cardiac hemodynamics, and 2000-m performance, with no between-groups difference in changes over time. However, HIIT_APR resulted in a lower interindividual variability in adaptations in ${\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ and related physiological parameters, but this is not the case for athletic performance, which can depend on a multitude of factors beyond physiological parameters. Conclusions : Results demonstrated that expressing supramaximal interval intensity as a proportion of APR facilitates imposing the same degrees of homeostatic stress and leads to more homogeneous physiological adaptations in maximal variables when compared to prescribing a supramaximal HIIT intervention using ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ . However, lower interindividual variability would be seen in submaximal variables if HIIT interventions were prescribed using ${\mathrm{W}\dot{\mathrm{V}}\mathrm{O}}_2\text{max}$ .

Purpose: This study investigated the postactivation performance-enhancement effect of maximal voluntary isometric contraction (MVIC) at the starting position on power-clean performance over a series of contrast sets. Methods: Eighteen male (age: 31 [3.7] y, body mass: 76.8 [9.1] kg, height: 175.0 [5.2] cm) and 2 female (age: 27.5 [3.5] y, body mass: 53.3.8 [2.0] kg, height: 158.5 [4.9] cm) resistance-trained individuals performed a contrast postactivation performance-enhancement protocol (isometric contrast training condition [ISO]) consisting of 3 sets of 3 MVICs alternated with 3 power cleans, with an intracontrast rest period of 1 minute. A control protocol consisted of 3 sets of 3 power cleans were performed in a separate session. Barbell velocity during the power clean was measured as an indicator of performance. Results: A significant time effect was observed for both mean velocity (MV; P < .001) and peak velocity (PV; P = .008). Time × group (P = .415–.444) and group (P = .158–.210) effects showed no significant difference for either MV or PV. However, differences in MV and PV between the corresponding sets of ISO and control condition exceeded the minimum worthwhile change, showing a small to moderate effect (MV: d = 0.38–0.50, PV: d = 0.35–0.50) in favor of ISO. There was no significant difference in rating of perceived exertion between conditions (P = .385, d = 0.22). Conclusion: Power-clean performance was potentiated after 1 minute of rest following 3 repetitions of MVIC across 3 sets. Furthermore, the ISO protocol did not result in greater perception of exertion. These results indicate that coaches may incorporate MVICs as the postactivation performance-enhancement stimulus during contrast training involving the power-clean exercise.

Purpose: To compare the effects of unilateral flywheel training (FT), using a rotational conical pulley, including multidirectional movements with either preplanned or random unanticipated/unexpected executions on functional performance in football players. Methods: A total of 32 young male football players were randomly assigned to an FT program including preplanned unilateral multidirectional movements (PTG, n = 11), an FT executing the same unilateral movements through random (ie, right or left leg) unanticipated (ie, verbal or visual cue) or unexpected (ie, moment where the cue was provided) situations (UTG, n = 11), or a control group (n = 10) that followed their football training routine. FT consisted of 1 set × 5–12 repetitions of 4 exercises performed once a week for 10 weeks. Intermittent endurance performance, repeated unilateral and bilateral jumping ability, change-of-direction (COD) ability, linear sprint velocity, preplanned repeated-sprint ability (RSA), and uncertainty RSA (RSA-RANDOM) were assessed preintervention and postintervention. Results: Significant improvements were found in RSA-RANDOM performance (P < .05, effect size [ES] range: UTG [1.83–2.16], PTG [0.69–0.73]) and COD (P < .05, ES: UTG = 1.34, PTG = 0.98]) in both training groups. Furthermore, significant improvements were also found in intermittent endurance performance (P = .016, ES = 0.37) and sprinting (P = .006, ES = 0.45) in UTG. No changes in any variable were found in the control group. No significant between-groups differences (P > .05) were reported between UTG and PTG, while differences were observed to the control group in unilateral jumping ability, COD, and RSA-RANDOM for UTG, and in RSA-RANDOM for PTG. Conclusions: A 10-week unilateral FT improved RSA-RANDOM and COD ability in youth football players, so both preplanned and unexpected situations should be included on strength training.