Frontiers in Sports and Active Living

BackgroundMaking quick, accurate decisions is crucial in competitive sports like softball, where perceptual-cognitive skills can significantly impact on-field performance. This study evaluates the long-term effectiveness of a targeted perceptual-cognitive training program, delivered through the uHIT platform, on improving batting performance in collegiate softball players. MethodsA longitudinal analysis was conducted on data collected from both NCAA and NAIA softball teams over multiple seasons. The study used Bayesian statistical methods to assess the impact of cognitive training on on-base plus slugging percentage (OPS). The analysis incorporated weighted models to account for variability in games played and differences between teams, and the influence of team and year-division effects was considered. Key metrics, including Decision AUC and Response Time, were tracked to evaluate perceptual-cognitive improvements. ResultsThe results demonstrated significant improvements in OPS for teams that participated in the cognitive training intervention, with the weighted models indicating a substantial effect of the training on performance. Notably, the intervention was most effective in teams with higher training intensity, as evidenced by the permutation test results. The Bayesian analysis also revealed that the intervention led to statistically significant improvements in decision-making and response times, translating into enhanced on-field performance. ConclusionThe findings support the effectiveness of perceptual-cognitive training in improving real-world athletic performance in softball. The uHIT platform, as an ecologically valid training tool, has demonstrated its potential to serve as a critical component of athletic development programs. Future research should explore the long-term retention of these cognitive gains and their application across different sports and competitive levels.

Navigating public environments requires adjustments to ones walking patterns to avoid stationary and moving obstacles. It is known that physical inactivity induces alterations in motor capacities, but the impact of inactivity on anticipatory locomotor adjustments (ALA) has not been studied. The purpose of the present study was to compare ALAs and related muscle co-contraction during a pedestrian circumvention task between active (AA) and inactive young adults (IA). Thirteen AA and thirteen IA were placed in a virtual environment simulating a public park. Participants circumvented virtual pedestrians walking towards them. Walking speed, onset of deviation, clearance, foot placement strategies and muscle co-contraction were analysed. IA exhibited slower walking speeds compared to the AA during circumvention condition but not during unobstructed walking condition. The distance at the onset of trajectory deviation was larger for IA. Both groups increased co-contraction for pedestrian circumvention at the ankle and left hip and IA displayed greater ankle co-contraction overall. No significant group differences were observed in minimum clearance. This study suggests that an inactive lifestyle influences ALAs by inducing a cautious behavior during pedestrian circumvention.

Background/AimsHigh occupational injury rates are reported in musicians, with a career prevalence of up to 89%. Fatigue and playing (over)load are identified as key risk factors for musicians injuries. Self-report fatigue management strategies in sport have demonstrated preventive effects. A self-report fatigue management tool for musicians was developed based on a Delphi survey of international experts and hosted in an online app. The aims of this study are to evaluate the content validity and uptake of this new tool, and explore associations between collected performance quality, physical/psychological stress, pain, injury and fatigue data. MethodsUniversity and professional musicians were asked to provide entries into the online app twice per week for one to six months. Entries into the app were designed to take 2-3 minutes to complete and consisted of the following: 6 questions regarding playing load over the previous 72 hours; 5 questions regarding current levels in key physical/psychological stress domains (sleep, recovery, overplaying, pain, fitness); one question self-rating of performance quality over the previous day; one question regarding current musculoskeletal symptoms; a reaction time task to evaluate psychomotor fatigue. ResultsN=96 participants provided an average of 2 app entries (range 0 - 43). Increased playing time, rating of perceived exertion (RPE), and feelings of having to play too much were consistently associated with increased self-rated performance quality (p[&le;] .004; 6.7<|t|<2148.5). Increased ratings of feeling fit and recovering well were consistently associated with reduced pain severity (p<.001; 3.8<|t|<20.4). Pain severity was increased (6.5/10 vs. 2.5/10; p<.001) in participants reporting playing-related musculoskeletal disorders (PRMDs; symptoms affecting playing). ConclusionThe prospective value of regular individual self-report playing load, stress, and performance data collection in musicians is clear. However, limited uptake of the online fatigue management app piloted in this study indicates that new approaches to the collection of these data are needed to realize their potential impact.

ObjectivesA pitching motion involves three-dimensional whole body movement. Proper pelvic and trunk rotation movement are important for the prevention of throwing injuries. Given that throwing is not a simple rotation movement, the evaluation of proper motion should reflect muscle strength as well as coordination and pitching motion characteristics. We have devised a throwing rotational assessment (TRA) as a new evaluation of the total rotation angle required for throwing. The purpose of this study was to examine the characteristics of players with throwing disorders compared to a pain-free group using TRA. Materials and methodsThe subjects consisted of 164 high school baseball pitchers who participated in a medical check. Pain-induced tests included an elbow hyperextension test and an intra-articular shoulder impingement test. Pitchers who felt pain in either test were classified into a disorder group (n=61). With the subjects in a position similar to the foot contact phase of throwing, the rotation angles of the pelvis and trunk were measured. All tests were performed in the throwing and opposite directions. ResultsThe disorder group had significantly lower average rotation angles of the pelvis and trunk in the throwing direction and the rotation angle of the trunk in the opposite direction compared to the healthy group. ConclusionTRA reflects the complex whole body rotation movement. Reductions in rotational angles as assessed in TRA may be associated with throwing disorders. TRA is a simple method that may be useful in the early detection of a throwing disorder and could be used in the systematic evaluation during a medical check, as well as during self-check in the sports field.

This study aimed to determine the acute effects of static stretching of the hamstrings on maximal sprint speed and its spatiotemporal variables, and lower limb kinematics during the late swing phase, and its relationship with Nordic hamstring strength. Sixteen healthy male college sprinters were asked to sprint 80 m without static stretching and with static stretching of the hamstrings for 120 s per leg before the sprint, and both conditions were counterbalanced. The knee flexion peak force and torque were measured using the Nordic hamstring. The differences between no static stretch and static stretch, and their relationship with Nordic hamstring strength were investigated. The results showed that the touchdown distance and support time increased, and flight distance decreased in under static stretch conditions with a decrease in maximal sprint speed. Moreover, under static stretch conditions, the angular velocity of knee extension at contralateral release was lower, while the theoretical hamstring length (difference between knee angle and hip angle) at ipsilateral touchdown was greater. In addition, the lower the peak force and torque of the Nordic hamstring, the more significant the decrease in maximal sprint speed, increase in support time, decrease in flight distance, and decrease in peak angular velocity of hip extension at static stretch. Furthermore, the more significant the decrease in maximal sprint speed at static stretch, the smaller the peak theoretical hamstring length at the no static stretch. Therefore, it is suggested that long- term static stretching immediately before sprinting in sprinters with poor Nordic hamstring strength and low hamstring compliance during the late swing phase may induce unfavorable kinematics to prevent hamstring strain injury and maximal sprint speed reduction.

Post-Activation Potentiation is a phenomenon by which muscular performance characteristics are acutely enhanced as a result of their previous contractile actions. It has been shown how Post-Activation Potentiation, which is usually evoked through heavy resistance exercise, has the potential to improve many different power performances, such as sprinting and jumping. Due to an easier applicability, some studies explored the potential of plyometric muscular actions to evoke the effects of Post-Activation Potentiation. Despite some findings on acceleration running performance, to the authors best knowledge, no studies investigated the effects of Post-Activation Potentiation on deceleration performance, which is a key factor in sports involving change of directions. Therefore, the aim of this study is to investigate the influence of a plyometric exercise protocol to a subsequent deceleration running performance. University soccer players (n = 18) performed 7 deceleration trials: at baseline and after [~] 15 seconds, 2, 4, 8, 12 and 16 minutes a walking control condition (C) or 3 sets of 10 repetitions of alternate-leg bounding (plyometric, P). Results show that no significant differences were found at any of the trials of the control condition (C) in comparison to the relative baseline. In the plyometric condition (P), the deceleration performance executed 2 minutes after the plyometric activity resulted significantly faster compared to the relative baseline (p = 0.042; ES = 0.86, large effect; % of improvement = 4.13 %). Therefore, the main findings of this study showed that a plyometric exercise has the potential to improve a subsequent running deceleration performance in soccer players, if an adequate recovery between these activities is provided to the players. These findings encourage further future investigations about the possible potentiating effects of plyometric activities on more complex actions like changes of direction and agility.

An acute bout of aerobic exercise (AAE) performed before practicing a motor task can enhance skill acquisition and motor learning. To date, research on the effects of AAE on motor learning has focused exclusively on concentric cycling, leaving the impact of eccentric cycling unexplored. Unlike concentric cycling, eccentric cycling involves muscle lengthening while resisting the reverse movement of the pedals and is characterized by greater force production with lower cardiovascular and metabolic cost. Regarding neuroplasticity changes, eccentric contractions induced a prolonged decrease in intracortical inhibition compared to concentric contractions. Eccentric cycling AAE also increases activation in cognitive-related regions. Given the involvement of these regions and motor cortex excitability in motor learning, we hypothesized that eccentric cycling AAE would enhance motor learning to a greater extent than concentric AAE. A total of 60 young healthy individuals were allocated to one of three groups that performed 20 min of: i) eccentric cycling; ii) concentric cycling; or iii) seated rest. Both cycling AAE conditions were performed at a power equivalent to 70% peak heart rate (i.e., moderate intensity). A continuous tracking task was used to assess motor skill acquisition (immediately after the intervention) and motor learning (48 h retention test). For both acquisition and retention, the eccentric group outperformed both the concentric and rest groups, while the concentric group also showed a better performance compared to the rest group at retention. Thus, we demonstrated that eccentric cycling AAE enhances motor learning to a greater extent than concentric cycling AAE, while also confirming previous work that showed enhanced motor learning following concentric cycling AAE compared to rest. Our findings suggest that eccentric cycling AAE may have important implications for exercise protocols prescribed in sports-related and clinical contexts. HighlightsO_LIEccentric cycling enhanced motor learning to a greater extent than concentric cycling C_LIO_LIEccentric and concentric cycling enhanced motor learning more than rest C_LIO_LIEnhanced skill acquisition occurred after eccentric cycling, along with lower heart rate response and perceived effort. C_LIO_LIEccentric cycling may have important implications in sports-related and clinical contexts C_LI

The optimal intra-set rest in cluster sets (CLS) plyometric-jump training (PJT) to improve physical fitness remains unclear. Thus, this study compared the effects of PJT with traditional (TRS) vs. CLS structures using different intra-set rests on physical fitness components. Forty- seven recreationally active young men performed 3-5 sets of 10-12 repetitions of upper- and lower-body exercises twice a week for six weeks using different set configurations as the TRS group (no intra-set rest), and the CLS10, CLS20 and CLS30 groups with 10, 20 and 30 s intra-set rest, respectively, while the total rest period (i.e., 180 s) was equated. Testing was carried out 48 h before and after the intervention and the rating of fatigue (ROF) was also assessed 20 min after the first and last session. There was no significant difference in the mean energy intake between groups (p > 0.05). The ANCOVA revealed that all groups showed similar improvements (p < 0.05) in body mass, body mass index, fat-free mass, one repetition maximum (dynamic strength) and repetitions to failure (muscular endurance) in back squat and chest press, handgrip strength, standing long jump, 20 m sprint, and 9-m shuttle run (change of direction speed), whereas the ROF decreases were greater in the CLS20 and CLS30 groups (p < 0.05). Compared to the TRS structure, six weeks of PJT with an intra-set rest of 20 s, or 30 s induced similar improvements in the measures of physical fitness and anthropometrics, with lower exercise-induced fatigue perception.

BackgroundThe purpose of the study was to investigate the effects of rock climbing experience on time to fatigue (TTF), finger flexor force production relative to body weight (REL FP), and changes in finger flexor muscle activity during tread wall climbing. MethodsEight advanced and seven novice sport rock climbers performed a climbing protocol on a treadwall system. The protocol consisted of climbing for six 5-minute intervals or until voluntary failure. A mounted force plate was used to measure finger force production before and after the climbing protocol. Subjects performed a 20-second maximum voluntary isometric contraction (MVIC) against the force plate with the dominant and non-dominant fingertips in a common climbing hand configuration known as a half crimp. Muscle activity was monitored with electromyographic electrodes placed bilaterally over the subjects flexor digitorum superficialis. Median frequency (MF) and root mean square (RMS) were analyzed. The treadwall was set at a difficulty of 9 IRCRA/5.9 YDS. It rotated at 7 m/min and was fixed at 7{degrees} overhanging. ResultsSignificant group differences were observed in subject characteristics, TTF (30{+/-}0 vs. 25.7{+/-}3.6 min), REL FP (5.6{+/-}1.2 vs. 3.2{+/-}0.9 N/kg BW), {Delta}FP (+1.5{+/-}12.3% vs. -31{+/-}16%), and {Delta}MF (+6.3{+/-}22.4% vs. -17.6{+/-}10.9%). ConclusionThe results of this study demonstrate that advanced climbers possess greater finger flexor force production and resistance to fatigue compared to novices during bouts of climbing on a treadwall system. This may be attributed to physiological changes due to years of training, such as metabolic adaptations and oxygenation capacity in the forearm musculature.

ObjectiveThis pilot study aimed to assess the efficacy of a 16-week at-home high-intensity interval training (HIIT) program among individuals with spinal cord injury (SCI). MethodsEight individuals (age: 47{+/-}11 (SD) years, 3 females) with SCI below the sixth thoracic vertebrae participated in a 16-week at-home HIIT program using an arm ergometer. Participants completed baseline graded exercise tests to determine target heart rate zones. HIIT was prescribed thrice per week. Each training session consisted of six one-minute bouts with a target heart rate [~]80% heart rate reserve (HRR), interspersed with two minutes of recovery at [~]30% HRR. A portable heart rate monitor and phone application provided visual feedback during training and allowed for measurements of adherence and compliance. Graded exercise tests were completed after 8 and 16 weeks of HIIT. Surveys were administered to assess participation, self-efficacy, and satisfaction. ResultsParticipants demonstrated a decrease in submaximal cardiac output (P=0.028) and an increase in exercise capacity (peak power output, P=0.027) following HIIT, indicative of improved exercise economy and maximal work capacity. An 87% adherence rate was achieved during the HIIT program. Participants reached a high intensity of 70% HRR or greater during [~]80% of intervals. The recovery HRR target was reached during only [~]35% of intervals. Self-reported metrics of satisfaction and self-efficacy with at-home HIIT scored moderate to high. ConclusionParticipants demonstrated an improvement in exercise economy and maximal work capacity following at-home HIIT. Additionally, participant adherence, compliance, satisfaction, and self-efficacy metrics suggest that at-home HIIT was easily implemented and enjoyable.

PurposeWe used commercially available wearable devices that measure running power (foot- vs. wrist-based) and muscle oxygenation to investigate time-to-exhaustion during level and uphill running at critical intensity. Methods14 healthy recreational runners participated in this study. They first ran a 3-minute all-out test to derive their critical running intensity. They then performed two time-to-exhaustion trials (TTEs) at this intensity at separate slopes to assess time-to-exhaustion, muscle oxygenation, and rating of perceived exertion. ResultsWe observed a shorter time-to-exhaustion (539 {+/-} 160 vs. 936 {+/-} 336 s), a faster decline in muscle oxygenation over time (-2.48 {+/-} 1.32 vs. -1.62 {+/-} 2.11 %{middle dot}min-1), a higher rating of perceived exertion at matched time points, and a higher estimated metabolic rate (19.51 {+/-} 1.99 vs. 17.82 {+/-} 1.62 W{middle dot}kg-1) for the level time-to-exhaustion test (TTELevel) compared to the uphill time-to-exhaustion test (TTEIncline) at a 2.86{degrees} (5%) slope. ConclusionOur data suggests that athletes should be careful when using running power at critical intensity to guide their racing and training in non-level conditions.

PurposePre-muscle contraction improves sports performance because post-activation potentiation (PAP), induced by a previous intense voluntary contraction (conditioning contraction), amplifies the subsequent target muscle contraction. This study aims to examine the influence of conditioning contraction on the performance of ballistic motion, particularly on the stretch-shortening cycle (SSC). MethodsFourteen male university students specializing in athletic jumping events performed a drop jump from a height of 0.3 m. Maximal voluntary isometric plantarflexion for 6 seconds was considered a conditioning contraction. We set two conditions: in the PAP condition, participants performed a conditioning contraction 10 s before the drop jump, and in the control condition, they simply performed the drop jump. After 10 minutes of rest from the reference drop jump, both conditions were performed. A 3D motion analysis system, force plates, and surface electromyography were used to record the jump data. ResultsIn the PAP conditions, the jump height and velocity of the center of gravity increased by 4 cm and 14 cm/s, respectively. Lower limb torque increment was observed only in the ankle joint between the PAP and control conditions (0.31 Nm/kg). However, there was no change in the magnitude of muscle activity based on the electromyogram. ConclusionOur study showed that PAP could potentiate the contraction mechanism under excitation-contraction coupling, irrespective of the effect on the central nervous system. Therefore, PAP enhances jump performance by improving SSC.

Acute aerobic exercise (AEX) can enhance motor learning. While AEX intensity likely plays a key role, there is mixed evidence for AEX-enhanced motor skill acquisition and learning across a spectrum of exercise intensities. This may stem, in part, from inconsistent AEX parameters (i.e., intensity, structure, and duration) employed within and across studies. Additionally, evidence suggests that AEX can enhance a specific form of motor learning, namely motor adaptation. Moderate- and high-intensity AEX can increase motor adaptation, but evidence remains limited and inconsistent. Hence, the impact of AEX intensity on motor adaptation remains unclear. Here, we investigated the influence of AEX intensity on motor adaptation, while controlling for AEX structure and duration. Eighty young adults were assigned to four cycling AEX/Rest groups (n=20/group): 20 min of light (LIIT), moderate (MIIT), or high (HIIT) intensity interval training, or Rest (control). AEX consisted of four 3-min cycling intervals (LIIT, 35% heart rate reserve [HRR]; MIIT, 55%HRR; HIIT, 80%HRR) and 2-min active recovery (25%HRR). Participants practiced a visuomotor rotation task immediately after AEX/Rest (adaptation) and at a no-AEX 24 h retention test (motor learning). We found that: (1) all AEX intensities enhanced motor learning compared to Rest, and (2) HIIT enhanced motor adaptation and learning to the greatest extent, followed by MIIT then LIIT. This is the first study to demonstrate a dose-response effect of AEX intensity on motor adaptation and learning. Our results highlight the importance of considering intensity when prescribing AEX in sports and clinical contexts to promote motor learning.

The aim of this study was to determine which physiological variables could predict performance during a CrossFit competition. Fifteen male CrossFit athletes (35 {+/-} 9 years) participated and performed a series of tests (incremental load test for full squat and bench press, jump tests, incremental running test, and Wingate test) that were used as potential predictors of CrossFit performance. Thereafter, they performed the five Workouts of the Day (WODs) corresponding to the CrossFit Games Open 2019, and the relationship between each variable and CrossFit performance was analyzed. Overall Crossfit performance (i.e., final ranking considering all WODs) was significantly related to jump ability, mean and peak power output during the Wingate test, relative maximum strength for the full squat and the bench press, and maximum oxygen uptake and maximum speed during an incremental running test (all p<0.05, r=0.58-0.75), although the relationship of most markers varied depending on the analyzed WOD. Multiple linear regression analysis showed that the combination of maximum oxygen uptake, squat jump ability, and reactive strength index accounted for 81% of the variance in overall CrossFit performance (p=0.0003). CrossFit performance seems dependent on a variety of power-, strength-, and aerobic-related markers, which reflects the complexity of this sport. Improvements in aerobic capacity may help people and athletes in CrossFit performance and well-being. Also, focus on lower body power could be the key to obtain better performance markers.

Individuals with high fatigue resistance against a high-intensity conditioning activity (CA) may be able to avoid experiencing significant fatigue and enhance their voluntary performance. We examined whether the optimal contraction duration of dynamic knee extension exercises to maximize subsequent voluntary performance varies depending on the strength level of an individual. The study participants were 22 male American college football players. Initially, all participants performed a 10-s maximal isometric knee extension exercise and were classified as stronger individuals (n = 8) and weaker individuals (n = 8) based on their relative muscle strength. Each group then performed three types of dynamic CA with different contraction durations (6 s [6-CA], 12 s [12-CA], and 18 s [18-CA]) in random order. To observe the time-course changes in post-activation potentiation and performance enhancement, the twitch torques induced by electrical stimulation and isokinetic knee extension torques at 180{degrees}/s were recorded before and after each CA. The twitch torque increased at 10 s (29.5% {+/-} 9.3%) and 1 min (18.5% {+/-} 6.8%) after 6-CA for the stronger individuals (p < 0.05). However, no post-activation potentiation was induced in the weaker individuals in either protocol. Voluntary performance increased at 4 (7.0% {+/-} 4.5%) and 7 (8.2% {+/-} 4.3%) min after 18-CA for stronger individuals (p < 0.05). However, there was no post-activation performance enhancement in either protocol for weaker individuals. Thus, CA with a relatively long contraction duration was optimal to maximize the subsequent voluntary performance for stronger individuals. It remains unknown whether CAs performed with relatively short or long contraction durations were optimal for weaker individuals.

Severe-intensity constant work rate (CWR) cycling tests are useful for monitoring training progression and adaptation as they impose significant physiological and psychological strain and thus simulate the high-intensity competition environment. However, fatiguing tests require substantial recovery and may disrupt athlete training or competition preparation. Therefore, the development of a brief, minimally fatiguing test providing comparable information is desirable. PurposeTo determine whether physiological variables measured during, and functional decline in maximal power output immediately after, a 2-min CWR test can act as a proxy for 4-min test outcomes. MethodsPhysiological stress was monitored and pre-to-post-CWR changes in 10-s sprint power computed (to estimate performance fatigability) during 2- and 4-min CWR tests in high-level cyclists. ResultsThe 2-min CWR test evoked a smaller decline in sprint mechanical power (32% vs. 47%, p<0.001), however both the physiological variables and sprint mechanical power were independently and strongly correlated between 2- and 4-min tests. Differences in V{middle dot}O2peak and blood lactate concentration in both CWR tests were strongly associated with the decline in sprint mechanical power. ConclusionPhysiological variables measured during, and the loss in sprint mechanical power measured after, a severe-intensity 2-min CWR test were less than in the 4-min test. Yet strong correlations between 2- and 4-min test outcomes indicated that the 2-min test can be used as a proxy for the longer test. Because shorter tests are less strenuous, they should have less impact on training and competition preparation and may therefore be more practically applicable within the elite performance environment.

OBJECTIVEThis study explores the effects of physical activities on cognitive performance in healthy subjects, specifically evaluating Serial Subtract 7 Test (SST) performance during a cognitive-stepping dual task influenced by the 6-Minute Walking Test (6MWT) with and without music. METHODSA controlled experiment was conducted using the Ambulosono device to standardize walking exercises. 54 high school students participated, undergoing the 6MWT in different scenarios: Verbal 6-Minute Walking Test (6MWT) or Music-Guided Walking (MU). Final data from 43 students was used in the analysis. The SST measured cognitive changes in both single-task and dual-task conditions. RESULTSThe 6MWT significantly enhanced cognitive performance in both single and dual-task conditions. However, the addition of music did not show a substantial improvement in cognitive performance. The findings indicated the positive impact of 6MWT on cognitive abilities, irrespective of musical accompaniment. CONCLUSIONSThis research contributes to the understanding of how physical exercises can modulate cognitive functions in healthy individuals. It highlights the potential of 6MWT in enhancing cognitive performance, suggesting further exploration into the role of physical activity in cognitive health.

ObjectiveThis study aims to investigate the effects of combining medial collateral ligament (MCL) reconstruction surgery with proprioceptive neuromuscular facilitation (PNF) training on knee joint function and rehabilitation outcomes. Based on these findings, relevant clinical recommendations are proposed. MethodsA mixed-method approach was employed, incorporating literature review, experimental design, statistical analysis, and comparative evaluation. ResultsCompared to the control group, patients in the PNF group demonstrated significantly greater range of motion (ROM) and knee flexion (P < 0.01), experienced faster reduction in pain (P < 0.01), and showed superior physical recovery (P < 0.01). Overall rehabilitation outcomes were also rated more favorably in the PNF group (P< 0.01). ConclusionPNF training contributes significantly to the improvement of knee joint stability and motor control in patients with MCL injuries, particularly by strengthening muscles associated with the medial collateral ligament.This clinical trial was registered (https://www.clinicaltrials.gov). The trial number is ChiCTR2500105207. RecommendationsFuture research should focus on the effectiveness of PNF training for different types of injuries, explore the impact of varied PNF parameters on MCL rehabilitation, and assess the combined efficacy of PNF with other rehabilitation interventions to maximize its utility in sports medicine.

IntroductionCycling performance is influenced by hip flexor and extensor muscle strength. While belt stabilised handheld dynamometers (B-HHD) are valid for measuring isometric hip muscle strength, fixed frame dynamometers are becoming popular, offering potentially better stability and reliability. However, the reliability of both devices has not been examined in cyclists. This study evaluated the test-retest reliability and agreement between a B-HHD (MicroFET2, Hoggan Scientific) and a fixed-frame dynamometer (ForceFrame (FF) Max, Vald Performance) for hip flexion and extension peak force measurement in cyclists. MethodsA test-retest design was used. Twenty-five recreational cyclists (age {+/-} SD: 36.64 ({+/-}12.34) years; 22 males) were tested twice, approximately 72 hours apart. Three unilateral maximal voluntary isometric contractions (MVIC) of the hip flexors and extensors of each limb were performed, using the B-HHD and FF in a random order. Within and between session reliability was determined using Intraclass correlation coefficients 3.1 & 3.k. Standard error of measurements (SEM) and minimal detectable changes (MDC) were calculated. Agreement was assessed using 95% limits of agreement (LOA). ResultsFor hip flexion, within and between session reliability was good to excellent, and SEMs were similar (B-HHD ICCs = 0.77-0.93, SEMs = 14.25-22.71N (7.19-10.38%); FF ICCs = 0.77-0.95, SEMs = 7.80N-18.98N (3.47%-8.54%)). FF MDCs were lower within-session (21.61-39.48N (9.60-17.97%)) than B-HHD MDCs (39.50-62.95N (19.94-28.78%)), but similar between-sessions (FF MDCs= 41.25-52.61N (19.42-23.66%); B-HHD MDCs 41.21N-48.95N (18.53-23.77%)). For hip extension, both devices demonstrated good to excellent reliability and SEMs were similar (B-HHD ICCs = 0.90-0.95, SEMs = 15.77-21.53N ( 7.38-9.96%); FF ICCs = 0.85-0.95, SEMs =19.21-29.05N (7.82-11.78%) within and between sessions). All LOA exceeded a 20N acceptability threshold. ConclusionBoth devices are reliable in recreational cyclists, but large MDCs suggest that caution is needed when interpreting repeated measurements. Both devices cannot be used interchangeably due to poor agreement.

Intensity is a key component of exercise prescription. However, balance training intensity is not well defined. Consequently, balance training studies often do not report exercise intensity, which hinders implementing these interventions and developing exercise guidelines. This study aimed to validate measures of reactive balance training intensity. Healthy young (n=11) and older (n=9) adults experienced moving platform balance perturbations of varying magnitudes. Candidate intensity measures were: number of reactive steps; centre of mass displacement, velocity, and acceleration, and margin of stability 100 ms post-perturbation; peak electrodermal response; and OMNI Perceived Exertion Scale and Balance Intensity Scale scores. Correlations were examined between perturbation magnitude and candidate intensity measures. We also compared candidate intensity measures between backward- and forward-fall perturbations and between age groups using generalized linear mixed models. Peak centre of mass acceleration 100 ms after the perturbation was significant positively correlated with perturbation magnitude, with no significant age-group or direction effects, suggesting that this is a valid measure of absolute perturbation intensity. Number of reactive steps, peak electrodermal response, and OMNI Perceived Exertion Scale and Balance Intensity Scale scores were significantly positively correlated with perturbation magnitude, and were significantly higher for backward-fall compared with forward fall perturbations and for older adults compared to younger adults at the same magnitude, suggesting that these are valid measures of relative perturbation intensity. These measures could be used to prescribe and report intensity of reactive balance training in future studies.