Jump and sprint force velocity profile of young soccer players differ according to playing position.

Our study aimed to compare explosive performance and underlying mechanical determinants explored through F-V profiles in jumping and sprinting among young soccer players based on their playing position. Ninety elite soccer players were categorized into the following positions: goalkeepers, central defenders, wide defenders, central midfielders, wide midfielders, and forwards. Two testing sessions were conducted to measure the 30-metre sprint time (T30) using an over-ground sprint test and jump height (Hmax) through the SJ test. Results demonstrated performance variations among positions. In sprinting, forwards showed greater T30 (4.5 ± 0.14 s) compared to other positions, with goalkeepers exhibiting the lowest T30 (4.86 ± 0.18 s). Forwards also displayed higher maximal theoretical velocity (8.8 ± 0.4 m.s-1) and power output (Pmax) (19.4 ± 2.6 W.kg-1) than other positions, while goalkeepers had the lowest Pmax (16.5 ± 2 W.kg-1). In jumping, forwards (33.2 ± 3.9 cm) and wide-midfielders (33.6 ± 3.8 cm) achieved higher Hmax compared to goalkeepers (29.2 ± 5 cm) and central-midfielders (29.2 ± 3.8 cm). Wide-midfielders (28.5 ± 4.8 W.kg-1) and forwards (27.1 ± 4.3 W.kg-1) surpassed goalkeepers (23 ± 2.8 W.kg-1) and central-midfielders (25.1 ± 3.8 W.kg-1) in Pmax. Our findings reveal substantial position-related disparities in F-V profiles among elite young soccer players, in sprinting and jumping emphasizing the need for position-specific training programmes to optimize player development and on-field performance from an early age.

Neuromuscular fatigability amplitude and aetiology are interrelated across muscles.

NEW FINDINGS: What is the central question of this study? Is neuromuscular fatigability interrelated between different muscle groups from the same individual during isometric all-out exercise? What is the main finding and its importance? Although the average decrease can vary between muscles, an individual demonstrates interrelated fatigability aetiology regardless of the muscle group tested. The inter-individual variability provides evidence of different profiles common between muscles, which can be regarded as an individual characteristic. ABSTRACT: Neuromuscular fatigability is commonly attributed to central and peripheral origins. However, there is strong evidence of interactions between these two mechanisms. According to the idea that peripheral fatigability might be centrally regulated, one can hypothesize that neuromuscular fatigability would be correlated between different muscle groups at the individual level. Thirty-two healthy participants (16 women and 16 men) completed two 5 min fatiguing exercises [60 isometric maximal voluntary contractions (MVCs)] with finger flexors (FFs) and ankle plantar flexors (PFs) in two randomized sessions. Neuromuscular testing was conducted before, during (every six MVCs) and directly after the fatigue procedure. The force asymptote (FA ) was calculated as the asymptote of the force-time relationship. Changes (post- vs. pre-fatigue) in the exercise-evoked force (ΔDb100 ), voluntary activation (ΔVA) and central activation ratio (∆CAR) were also investigated. Significant correlations were found between FFs and PFs for FA , ΔDb100 and ΔVA (r = 0.65, r = 0.63 and r = 0.50, respectively). A significant negative correlation between ∆CAR and ∆Db100 was evidenced for both PFs (r = -0.82) and FFs (r = -0.57). Neuromuscular fatigability is correlated between different muscle groups at the individual level. The results support the idea that a restrained motor drive prevents large peripheral perturbations and that individuals exhibit correlated fatigability aetiology regardless of the muscle group tested. Widely different central/peripheral profiles can be found amongst individuals, and a part of the fatigability aetiology can be regarded as an individual characteristic.

Methodological Considerations on the Relationship Between the 1,500-m Rowing Ergometer Performance and Vertical Jump in National-Level Adolescent Rowers.

Maciejewski, H, Rahmani, A, Chorin, F, Lardy, J, Samozino, P, and Ratel, S. Methodological considerations on the relationship between the 1,500-m rowing ergometer performance and vertical jump in national-level adolescent rowers. J Strength Cond Res 33(11): 3000-3007, 2019-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 (P1500) and a squat jump (SJ) test. The performance in SJ was determined by calculating the jump height (HSJ in cm), a jump index (ISJ = HSJ·body mass·gravity, in J), and the mean power output (PSJ 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 P1500 and jump scores. P1500 was significantly correlated with HSJ (r = 0.29, p ≤ 0.05), ISJ (r = 0.72, p < 0.0001), and PSJ (r = 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 PSJ and P1500 (1.15 and 1.04, respectively) indicates that BM could influence jump and rowing ergometer performances at the same rate, and that PSJ could be the best correlate of P1500. Therefore, the calculation of power seems to be more relevant than HSJ and ISJ 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.

Relationship between Force-Velocity Profiles and 1,500-m Ergometer Performance in Young Rowers.

Rowing races require developing high level of force and power output at high contraction velocity. This study determined the force-velocity and power-velocity (F-P-V) profiles of lower and upper limbs of adolescent rowers and their relationships with a 1,500-m rowing ergometer performance. The power developed during the 1,500-m (P1500) was evaluated in fourteen national-level male rowers (age: 15.3±0.6 yrs). F-P-V profiles were assessed during bench pull (BP) and squat jump (SJ) exercises. The theoretical maximal values of force (F0), velocity (V0), power output (Pmax) and the F-V relationship slope (S FV ) were determined. The body mass (BM) influence on these relationships was considered using an allometric approach. F0 was 720±144 and 2146±405 N, V0 was 1.8±0.1 and 1.8±0.3 m·s-1, Pmax was 333±83 and 968±204 W and SFV was -391±54 and -1,200±260 N·s·m-1 for BP and SJ, respectively. Upper and lower limb F0 and Pmax were significantly related. P1500 was significantly (P<0.05) correlated to V0-BP, F0-BP, SFV-BP, Pmax-BP, F0-SJ and Pmax-SJ (r²=0.29 to 0.79). BM accounted for more than 90% of these relationships. Rowers' F-P-V profiles reflect adaptations to chronic rowing practice. F-P-V profiles and rowing performance correlations suggest that BP and SJ exercises are relevant to evaluate young rowers' explosive abilities.

Sit to stand in elderly fallers vs non-fallers: new insights from force platform and electromyography data.

BACKGROUND: The sit-to-stand movement requires balance control and coordination between the trunk and lower limbs. For these reasons, it is commonly used in clinics for evaluating lower limb muscle function in the elderly. The aim of the present study was to point out re levant biomechanical and neurophysiological sit-to-stand parameters allowing comparison between elderly fallers and non-fallers. METHODS: Ten elderly fallers and thirty non-fallers performed sit-to-stand movements. Sit-to-stand mechanical (maximal and mean force, impulse) and temporal parameters were measured in the vertical and anteroposterior axes using force platforms. Activity of rectus femoris, vastus lateralis, and gastrocnemius lateralis muscles was bilaterally recorded by surface electromyography. RESULTS: Time to realize sit-to-stand movements was significantly longer in elderly fallers compared to non-fallers (p < 0.05). In the same way, maximal vertical force and mean posterior force applied on force platform were significantly lower (p < 0.05) in fallers than in non-fallers individual. At muscular activity level, results showed a main statistical difference in gastrocnemius lateralis muscle activity patterns between faller and non-faller groups. CONCLUSION: Vertical and anteroposterior data from force platform, and gastrocnemius lateralis muscle activity determined during sit-to-stand movement are the most relevant parameters to differentiate fallers and non-fallers. Moreover, these factors highlight different strategies to rise from a chair between faller and non-faller group, suggesting that fallers would constantly adjust their control balance during the sit-to-stand movement.

The 1,500-m Rowing Performance is Highly Dependent on Modified Wingate Anaerobic Test Performance in National-Level Adolescent Rowers.

PURPOSE: The 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. METHODS: Fourteen 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). RESULTS: PWIN was correlated to P1500 (r2 = .83, p < .0001, ß = 100%). Furthermore, the estimated total muscle mass was correlated to PWIN and P1500 (r2 = .72 and r2 = .83, p < .0001, ß = 100%, respectively). The allometric scaling also indicated that total muscle mass accounts 62% for the relationship between PWIN and P1500. CONCLUSION: Our 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.

Determination of reliable force platform parameters and number of trial to evaluate sit-to-stand movement.

BACKGROUND: Sit-to-stand (STS) movement is useful for evaluating lower limb muscle function, especially from force platforms. Nevertheless, due to a lack of standardization of the STS movement (e.g., position, subject's instructions, etc.), it is difficult to compare results obtained in previous studies. AIMS: The aim of the present study was to determine the most relevant condition, parameters, and number of trial to perform STS movements. METHODS: In this study, STS mechanical (maximal and mean force, impulse) and temporal parameters were measured in the vertical, medio-lateral and antero-posterior axes using a force platform. Five STS conditions (i.e., with or without armrests, variation of the height of the chair and the movement speed) were analyzed to evaluate repeatability of different standardized procedures. RESULTS: Most of the mechanical and temporal parameters were influenced by the STS condition (p < 0.05). Regarding vertical axis, results showed a strong to perfect repeatability for all parameters (0.72 < ICC < 0.9) for only one condition: STS performed as rapidly as possible with a 90° knee angle when seated, without using armrests. Regardless conditions of performance, our results also showed that the most repeatable parameters were mean and peak force in medio-lateral axis, and the impulse measured in the three directions. Three trials should be performed to reach high repeatability. CONCLUSION: Our results suggest that the fast condition, with a 90° knee joint angle, with arms crossed over the chest, is the most reliable condition to evaluate performance during STS movement.

Bioenergetical and Cardiac Adaptations of Pilots to a 24-Hour Team Kart Race.

This study aimed to evaluate energy expenditure (EE) and heart rate (HR) response in kart pilots to successive driving bouts during a 24-hour team race. Eight adult male pilots (22.8 ± 4.1 years) participated to a team 24-hour speedway kart race in Le Mans (France). They alternatively piloted a 390 cm kart. Each relay was 45 minutes long and each pilot performed 4 relays. For each pilot, mean speeds were calculated from lap-to-lap duration recordings using a telemetric infrared timing device. Heart rate values were recorded continuously on 5-second intervals using a portable cardiometric device. Total energy expenditure (EET) and physical activity ratio (PAR) were determined by accelerometry. To pilot a kart during 45 minutes at a mean speed around 62 km·h induces a 300-kcal EET, corresponding to a 5.6-Mets PAR. This effort is responsive for a 73 b·min increase in HR, from 84.1 ± 7.6 to 157.4 ± 11.0 b·min (82% maximal heart rate intensity). However, during this relay period, HR values seemed independent to mean speed performance and bioenergetical values. Thus, in the context of the 24-hour team race, the variability in effort made during each relay and relay succession did not alter bioenergetical adaptation of pilots to kart driving. The high EE and HR values would be better explained by both emotional stress and environmental constraints such as speedway configuration and vibrations. The way how these factors specifically influence bioenergetical demand, and their relative importance, has to be specified to optimize training procedure and recommendations.

Core stability is associated with dynamic postural balance in soccer players experiencing groin pain without time-loss.

Objectives: The study sought to evaluate possible relationships between dynamic postural balance and pain, core stability, and hip range of motion in soccer players who were experiencing groin pain (GP). Furthermore, the study aimed to compare these measurements in symptomatic and asymptomatic players. Methods: The study included 42 male soccer players experiencing GP and an equal number of asymptomatic players. Dynamic postural balance, pain, hip range of motion and trunk endurance were measured. Results: The GP group revealed reduced dynamic balance performance (p < 0.01-0.001) in injured and non-injured limbs compared to control group. Further, players experiencing GP demonstrated lower hip range of motion in internal (p < 0.05) and total rotations (p < 0.01) in the injured limb, and lower trunk endurance (p < 0.001) compared to their asymptomatic peers. In general, core stability was associated (r = 0.13-0.61, p < 0.05-0.001) with the poor dynamic balance performance in the GP group while standing on injured and non-injured limbs. No significant correlations between dynamic postural balance, pain and hip range of motion were observed. Conclusion: Poor core endurance was found to be associated with dynamic balance disorders in soccer players experiencing GP. This information can aid in the development of targeted strategies to enhance dynamic postural balance in these players.

Postural balance asymmetry and subsequent noncontact lower extremity musculoskeletal injuries among Tunisian soccer players with groin pain: A prospective case control study.

BACKGROUND: Recent studies reported postural balance disorders in patients and soccer players with groin pain (GP) compared to controls. Since postural balance asymmetry identified after an initial injury contributes for subsequent injuries, identification of this asymmetry in soccer players with GP may highlight the risk of sustaining subsequent noncontact lower extremity musculoskeletal injuries in these players. Therefore, the aims of this study were to (i) examine static and dynamic unipedal postural balance asymmetry in soccer players with GP compared to healthy ones, and (ii) quantify the risk of subsequent noncontact lower extremity injuries in these players. RESEARCH QUESTION: Do soccer players with GP exhibit higher static and dynamic unipedal postural balance asymmetry, and higher risk of sustaining subsequent injuries compared to controls? METHODS: In this prospective case control study, 27 soccer players with non-time loss GP (GP group: GPG), and 27 healthy ones (control group: CG) were enrolled. Static and dynamic unipedal postural balance asymmetry were evaluated with a force platform using symmetry index (SI), and Y-balance test (Y-BT), respectively. Additionally, subsequent noncontact lower extremity musculoskeletal injuries were tracked for 10 months. RESULTS: The GPG revealed higher (p < 0.01) SI in eyes closed condition, higher (p < 0.001) side-to-side asymmetry in anterior, posteromedial and posterolateral reach distances and in composite Y-BT score compared to CG. They showed lower (p < 0.001) composite score for injured limb and higher (p < 0.001) side-to-side asymmetry in posteromedial reach distance compared to the cut-off values of 89.6 % and 4 cm, respectively. Moreover, GPG exhibited higher odds (OR= 7.48; 95 % CI = 2.15, 26.00; p < 0.01) of sustaining subsequent injuries compared to CG. SIGNIFICANCE: The Y-BT should be instituted into existing pre-participation physical examinations to screen for soccer players with non-time loss GP at an elevated risk of sustaining subsequent injuries. This could help coaches and clinicians make valid return to play decisions.

Neuromuscular, Psychological, and Sleep Predictors of Cancer-Related Fatigue in Cancer Patients.

BACKGROUND: Cancer-related fatigue (CRF) is the most reported side effect of cancer and its treatments. This distressing sense of exhaustion critically impairs quality of life and can persist for years after treatment completion. Mechanisms of CRF are multidimensional (eg, physical, psychological, or behavioral), suggesting the need for a complex assessment. Nevertheless, CRF remains assessed mainly with 1-dimensional questionnaires. The purpose of this study was to test whether neuromuscular parameters enhance a model including well-known predictors of CRF. PATIENTS AND METHODS: Forty-five participants with cancer history completed self-assessment questionnaires about quality of life, CRF, sleep disturbances, and emotional symptoms. They also completed a 5-minute handgrip fatiguing test composed of 60 maximal voluntary contractions to assess neuromuscular fatigability. Hierarchical linear regression analyses were performed to determine whether the neuromuscular fatigability threshold improved the FA12 score prediction beyond that provided by anxiety/depression and sleep disturbances. RESULTS: The hierarchical linear regression analysis evidenced that a model including anxiety/depression, sleep disturbances, and neuromuscular fatigability explained 56% of CRF variance. In addition, the results suggest that the mechanisms leading to CRF may be different from one person to another. CONCLUSION: Results revealed that sleep disturbances, emotional symptoms, and neuromuscular fatigability were the most important CRF predictors in cancer patients. This information could be useful for healthcare professionals offering tailored, individual support to patients with CRF.

Postural balance impairment in Tunisian second division soccer players with groin pain: A case-control study.

OBJECTIVE: To compare postural balance outcomes between soccer players with and without groin pain (GP). DESIGN: Case-control study. SETTING: Laboratory. PARTICIPANTS: Fifty-four soccer players, 27 with GP (GP group: GPG) and 27 healthy ones (control group: CG). MAIN OUTCOME MEASURES: Static and dynamic postural balance were assessed with a force platform and Y-balance test (Y-BT), respectively. Hip abduction, internal rotation (IR), external rotation (ER) and total rotation (TR) of both limbs were evaluated. RESULTS: The GPG exhibited significant higher centre of pressure values in the bipedal posture only on the foam surface in eyes opened and closed compared to controls. Besides, they had lower anterior, posteromedial and posterolateral reach distances and composite Y-BT score on the injured limb (IL) compared to non-injured limb (NIL) and dominant-limb (DL) of the CG. Moreover, they showed lower abduction, IR, ER, and TR on the IL compared to NIL and DL. CONCLUSIONS: Dynamic unipedal postural balance disorder could be one of the limiting factors of performance in soccer players with non-time loss GP. Hence, postural balance data in these players could enable sport coaches and physical therapists to better understand the mechanisms contributing for performance decrease.

Assessing the contribution of lower limb mobilization, in the supine position, on shoulder-pelvis girdles dissociation.

BACKGROUND: Several articular, muscular and neurological diseases generate mobility loss in the shoulder and pelvis girdles. Joint mobilization contributes to improving shoulder-pelvis girdles dissociation, but current mobilization techniques are not always successful and standardized. A robotic medical device, DPA Med®, by inducing trunk mobilization through lower limb oscillation has been developed for producing such a shoulder-pelvis girdles dissociation and is already used worldwide in rehabilitation hospitals. RESEARCH QUESTION: To determine the optimal lower limb oscillation frequency that generated the best shoulder-pelvis girdles dissociation using the DPA Med® device. METHODS: Thirty healthy adult volunteers (mean age: 38.6 [SD 15.2] years, mean height: 174 [SD 11.9] cm, mean body mass: 70.3 [SD 14.7] kg) participated in this prospective study. A kinematic analysis quantified pelvic and shoulder girdle mobility (rotation and lateral tilt) at different DPA Med® frequencies, from 0.5 Hz to 1 Hz. A visual analysis of the lower limb movement was also performed, using video sensors, to better understand the kinematics involved. RESULTS: All DPA Med® frequencies have shown significant shoulder-pelvis girdles dissociation (p < 0.05). This study established an optimal oscillation frequency with the minimal interindividual variability at 0.808 Hz. It induced pelvic mobility similar to that of normal gait, in the transverse and frontal planes (10.3°, SD 2.9°, and 12.0°, SD 2.2°, respectively). This trunk mobility was achieved by producing a lemniscate-shaped motion in the lower limbs (an eight-shaped motion in the transverse plane). SIGNIFICANCE: This study has shown that the DPA Med® device is able to induce shoulder-pelvis girdles dissociation similar to that of normal gait and allowed to establish the existence of an optimal DPA Med® oscillation frequency for lower limb mobility at 0.808 Hz. Further studies are required to evaluate its potentially benefits on gait disorders.

Reliability of force-velocity relationships during deadlift high pull.

This study aimed to evaluate the within- and between-session reliability of force, velocity and power performances and to assess the force-velocity relationship during the deadlift high pull (DHP). Nine participants performed two identical sessions of DHP with loads ranging from 30 to 70% of body mass. The force was measured by a force plate under the participants' feet. The velocity of the 'body + lifted mass' system was calculated by integrating the acceleration and the power was calculated as the product of force and velocity. The force-velocity relationships were obtained from linear regression of both mean and peak values of force and velocity. The within- and between-session reliability was evaluated by using coefficients of variation (CV) and intraclass correlation coefficients (ICC). Results showed that DHP force-velocity relationships were significantly linear (R² > 0.90, p < 0.05). Within sessions and between sessions, mean and peak forces during DHP showed a strong agreement (CV < 3%, ICC > 0.94), mean and peak velocities showed a good agreement (CV < 9%, 0.78 < ICC < 0.92). It was concluded that DHP performance and its force-velocity relationships are highly reliable and can therefore be utilised as a tool to characterise individuals' muscular profiles.

Torque-velocity and power-velocity relationships during isokinetic trunk flexion and extension.

BACKGROUND: No study has reported the possibility of establishing torque-velocity and power-velocity relationships for both flexor and extensor trunk muscles. The present study therefore sought to assess these relationships during isokinetic exercise. METHODS: Nine healthy male subjects performed series of isokinetic trunk flexions and extensions at six different velocities ranging from 45 degrees s(-1) to 120 degrees s(-1). Trunk flexor and extensor muscles were, respectively, assessed on two separate days. All experiments used a Biodex dynamometer. FINDINGS: Torque-velocity relationships were significantly well described by a linear relationship for both trunk flexor (P<0.01; r=0.92-0.99) and extensor muscles (P<0.05; r=0.82-0.97) in all subjects. Power-velocity relationships exhibited a parabolic shape for all subjects (P<0.05; r=0.96-0.99) for both muscle groups. INTERPRETATION: Results showed that trunk muscle torque- and power-velocity relationships can be assessed during isokinetic exercise. The findings were in agreement with previous studies of lower and upper limbs. This kind of measurement can therefore be applied in assessing low-back pain patients during rehabilitation.

Importance of upper-limb inertia in calculating concentric bench press force.

The purpose of this study was to investigate the influence of upper-limb inertia on the force-velocity relationship and maximal power during concentric bench press exercise. Reference peak force values (Fpeakp) measured with a force plate positioned below the bench were compared to those measured simultaneously with a kinematic device fixed on the barbell by taking (Fpeakt) or not taking (Fpeakb) upper-limb inertia into account. Thirteen men (27.8 +/- 4.1 years, 184.6 +/- 5.5 cm, 99.5 +/- 18.6 kg) performed all-out concentric bench press exercise against 8 loads ranging between 7 and 74 kg. The results showed that for each load, Fpeakb was significantly less than Fpeakp (P < 0.0001), whereas no significant difference was found between Fpeakp and Fpeakt. The values of maximal force (F0), maximal velocity (V0), optimal velocity (Vopt), and maximal power (Pmax), extrapolated from the force- and power-velocity relationships determined with the kinematic device, were significantly underestimated when upper-limb inertia was ignored. The results underline the importance of taking account of the total inertia of the moving system to ensure precise evaluation of upper-limb muscular characteristics in all-out concentric bench press exercise with a kinematic device. A major application of this study would be to develop precise upper-limb muscular characteristic evaluation in laboratory and field conditions by using a simple and cheap kinematic device.

A Simple Method for Assessing Upper-Limb Force-Velocity Profile in Bench Press.

PURPOSE: To analyze the reliability and validity of a field computation method based on easy-to-measure data to assess the mean force ([Formula: see text]) and velocity ([Formula: see text]) produced during a ballistic bench-press movement and to verify that the force-velocity profile (F-v) obtained with multiple loaded trials is accurately described. METHODS: Twelve participants performed ballistic bench presses against various lifted mass from 30% to 70% of their body mass. For each trial, [Formula: see text] and [Formula: see text] were determined from an accelerometer (sampling rate 500 Hz; reference method) and a simple computation method based on upper-limb mass, barbell flight height, and push-off distance. These [Formula: see text] and [Formula: see text] data were used to establish the F-v relationship for each individual and method. RESULTS: A strong to almost perfect reliability was observed between the 2 trials (ICC > .90 for [Formula: see text] and .80 for [Formula: see text], CV% < 10%), whatever the considered method. The mechanical variables ([Formula: see text], [Formula: see text]) measured with the 2 methods and all the variables extrapolated from the F-v relationships were strongly correlated (r2 > .80, P < .001). The practical differences between the methods for the extrapolated mechanical parameters were all <5%, indicating very probably no differences. CONCLUSION: The findings suggest that the simple computation method used here provides valid and reliable information on force and velocity produced during ballistic bench press, in line with that observed in laboratory conditions. This simple method is thus a practical tool, requiring only 3 simple parameters (upper-limb mass, barbell flight height, and push-off distance).

A virtual model of the bench press exercise.

The objective of this study was to design and validate a three degrees of freedom model in the sagittal plane for the bench press exercise. The mechanical model was based on rigid segments connected by revolute and prismatic pairs, which enabled a kinematic approach and global force estimation. The method requires only three simple measurements: (i) horizontal position of the hand (x(0)); (ii) vertical displacement of the barbell (Z) and (iii) elbow angle (theta). Eight adult male throwers performed maximal concentric bench press exercises against different masses. The kinematic results showed that the vertical displacement of each segment and the global centre of mass followed the vertical displacement of the lifted mass. Consequently, the vertical velocity and acceleration of the combined centre of mass and the lifted mass were identical. Finally, for each lifted mass, there were no practical differences between forces calculated from the bench press model and those simultaneously measured with a force platform. The error was lower than 2.5%. The validity of the mechanical method was also highlighted by a standard error of the estimate (SEE) ranging from 2.0 to 6.6N in absolute terms, a coefficient of variation (CV) < or =0.8%, and a correlation between the two scores > or =0.99 for all the lifts (p<0.001). The method described here, which is based on three simple parameters, allows accurate evaluation of the force developed by the upper limb muscles during bench press exercises in both field and laboratory conditions.