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This study aimed to explore the relationship between the inter-limb differences in unilateral countermovement (CMJ) height and the inter-limb differences in bilateral CMJ force production, and to elucidate whether the self-reported preferred leg contributes more to force production than the non-preferred leg. Twenty-three senior basketball players performed in a single session eight unilateral CMJs (four with each leg) and four bilateral CMJs. Impulse, peak force, mean force were recorded during the bilateral CMJ, and jump height during the unilateral CMJ. Small correlations were observed between the inter-limb differences in unilateral CMJ height and the inter-limb asymmetries in bilateral CMJ impulse, peak force, and mean force (p ≥ 0.171; r≤-0.142). The self-reported preferred leg revealed a higher performance in 7 out of 23 participants (Kappa = −0.20) for the unilateral CMJ height, 7 out of 23 participants (Kappa = −0.11) for the bilateral CMJ impulse, 6 out of 23 participants (Kappa = −0.36) for the bilateral CMJ peak force, and 8 out of 23 participants (Kappa = −0.34) for the bilateral CMJ mean force. These results highlight that the asymmetries detected during bilateral CMJs cannot be extrapolated to unilateral CMJs, and that the preferred leg generally contributes less to force production than the non-preferred leg during both bilateral and unilateral CMJs. [ABSTRACT FROM AUTHOR]

This study aimed to determine whether the provision of jump height feedback (knowledge of result; KR) can increase the performance and the consistency of output variables. In a randomised order, sixteen participants performed six squat or countermovement jumps (three from a 90º knee angle and three from a self-preferred knee angle) with or without KR over four sessions. The provision of KR significantly increased peak force (p = 0.046, 1.83%), mean force (p = 0.037, 1.45%), peak velocity (p < 0.001, 3.71%), mean velocity (p = 0.004, 3.44%), peak power (p < 0.001, 4.22%) and mean power (p = 0.001, 4.69%). A high within-session reliability was observed for all variables (coefficient of variation [CV] ≤ 5.62%, intraclass correlation coefficient [ICC] ≥ 0.95). No systematic differences in reliability were detected between the jumps performed without KR (CV = 3.00 ± 1.38%, ICC = 0.97 ± 0.03) and with KR (CV = 3.04 ± 1.49%, ICC = 0.97 ± 0.04). These results suggest that the provision of jump height feedback during vertical jump testing is effective to enhance vertical jump performance but it does not reduce the variability between jumps. [ABSTRACT FROM AUTHOR]

This study aimed to compare the magnitude of the force-velocity (F-V) relationship parameters (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [Pmax]) between the squat jumps (SJ) performed from different knee angles. The F-V relationships of 12 men were assessed in 3 sessions during the SJ performed from a knee angle of 80° (SJ80), 90° (SJ90) and 100° (SJ100). The SJ100 provided likely to very likely higher values of F0 and Pmax compared to SJ80 (86% and 98%, respectively) and SJ90 (73% and 94%, respectively), while unclear and trivial differences were observed for the remaining comparisons. The magnitude of the correlations between the 3 SJ types was very large to nearly perfect for Pmax (r range = 0.864 to 0.940), moderate to very large for F0 (r range = 0.438 to 0.778), and small to large for V0 (r range = 0.361 to 0.642) and the F-V slope (r range = 0.178 to 0.645). These results suggest that the F-V relationship assessed during the SJ exercise is affected by the initial knee angle with the increase of the knee angle from 80° to 100° being associated with higher values of F0 and Pmax, while V0 remains unchanged. [ABSTRACT FROM AUTHOR]

Different thresholds have been used to determine the start of the force-time analysis during countermovement jump testing. This study examined the influence of the jump starting threshold on the reliability and magnitude of loaded countermovement jump (CMJ) performance variables. Seventeen males were tested during two sessions using five loading conditions (17–30–45–60–75 kg). The CMJ performance was analysed with a force platform. The initiation of the eccentric phase was defined as the first instant in which the vertical ground reaction force was below system weight by 10 N, 50 N, 1% of system weight (1%SW), 10% of system weight (10%SW) and five standard deviations of system weight minus 30 ms (5SDSW). The 50 N, 10%SW and 5SDSW provided a higher reliability for the mean values of velocity and power as well as for the temporal variables only during the eccentric phase compared to the 10 N and 1%SW threshold (CV ratio>1.15). The magnitude of several variables collected during both phases for the 50 N, 10%SW and 5SDSW thresholds significantly differed with respect to 10 N and 1%SW thresholds (p< 0.05). These results suggest that the jump starting threshold may influence both the reliability and magnitude of loaded CMJ performance variables, especially during the eccentric phase. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effect of the knee angle and loading condition on the magnitude and reliability of squat jump (SJ) performance variables. Thirteen male sport sciences students performed in a random order 4 SJ types (knee angle of 80º [SJ80], 90º [SJ90], 100º [SJ100], and self-preferred [SJpref]) against 3 external loads. The push-off distance (HpO), jump height (Hmax), maximum force (Fmax) and maximum power (Pmax) were obtained from force platform recordings. The HpO during the SJpref (43.4 ± 6.4 cm) was always between SJ90 (44.3 ± 4.8 cm) and SJ100 (40.5 ± 4.2 cm). The magnitudes of Hmax, Fmax and Pmax were comparable or higher during the SJpref. The increase of the knee angle was associated with larger values of Fmax and Pmax, but no significant differences were observed for Hmax. An acceptable reliability was observed for HpO (coefficient of variation [CV]≤5.09% and intraclass correlation coefficient [ICC]≥0.78), Hmax (CV≤6.06% and ICC≥0.84), Fmax (CV≤3.25% and ICC≥0.96) and Pmax (CV≤2.93% and ICC≥0.96). Reliability did not systematically differ between the 4 SJ types. In conclusion, the higher magnitudes and comparable reliability of the performance variables obtained during the SJpref support its use for testing lower-body ballistic performance against different loads. [ABSTRACT FROM AUTHOR]

This study aimed to explore the effect of the velocity and depth of the countermovement on vertical jump performance and the shape of the force-time curve. Seventeen university students performed two blocks of 18 countermovement jumps (CMJ) being instructed to jump for maximum height after performing the countermovement at a self-selected (SS-CMJ) or fast (F-CMJ) velocity. Each block consisted of six CMJ from a larger depth, six CMJ from a shorter depth, and six CMJ from a self-preferred depth. Mean and peak values of force, velocity and power, reactive strength index-modified (RSImod), jump height, and the shape of the force-time curve (unimodal or bimodal) were assessed. The F-CMJ provided a higher (mean and peak force, mean velocity, mean power, and RSImod) or comparable (peak power, peak velocity, and jump height) performance than the SS-CMJ. The shorter CMJ provided the highest values of mean and peak force, mean and peak power, and RSImod, while peak velocity and jump height were higher for the larger and self-preferred CMJ. The force-time curve was bimodal during the larger CMJ (100%) and unimodal during the shorter CMJ (65–88%). These results highlight that CMJ performance is influenced by the velocity and depth of the countermovement. [ABSTRACT FROM AUTHOR]

This study aimed to explore the differences in the load-velocity profile between three upper-body pushing exercises in men and women. The load-velocity profiles (from 20% to 100% of the one-repetition maximum [1RM] in 5% increments) of 24 sport sciences students (12 men) were randomly tested during the horizontal bench press (HBP), inclined bench press (IBP) and seated military press (SMP) exercises. The 1RM was higher for the HBP (men: 94.2 ± 14.6 kg; women: 45.4 ± 10.1 kg), followed by the IBP (men: 87.7 ± 11.6 kg; women: 41.6 ± 6.6 kg), and finally the SMP (men: 67.4 ± 7.8 kg; women: 37.3 ± 6.3 kg). The mean test velocity (i.e., averaged velocity of all loads) and the slope of the load-velocity profile were significantly different between exercises (SMP > IBP > HBP) and sexes (men > women). The correlations between the exercises were very high for the individual 1RM values (r range = 0.714–0.982), but lower correlations were observed for the mean test velocity (r range = 0.237–0.766) slope of the load-velocity profile (r range = 0.018–0.721), and velocity of the 1RM (r range = 0.004–0.446). These results confirm that men present higher velocities at low relative loads (i.e., %1RM) compared to women during upper-body pushing exercises. [ABSTRACT FROM AUTHOR]

This study aimed to compare the one-repetition maximum (1RM) and the velocity outcomes obtained against the same absolute and relative (%1RM) loads between the flat and arched bench press (BP) variants. Eleven competitive male powerlifters were evaluated in one session with the flat BP (natural lumbar arch and moderate scapular retraction) and in another session with the arched BP (pronounced lumbar arch and scapular retraction). An incremental loading test was used to determine the 1RM as well as the barbell's velocity against the different external loads. The main findings revealed that the 1RM did not significantly differ between the flat (115.9 ± 17.9 kg) and arched (115.7 ± 18.4 kg) BP variants (p = 0.942, effect size = 0.01), while there were no significant differences between BP variants either for the velocity outcomes obtained against the individual loads nor for the velocities associated with each %1RM (p > 0.05). These results suggest that competitive powerlifters do not necessarily present their higher 1RM performance using the arched BP variant. Finally, both BP variants could be used interchangeably when using movement velocity for testing upper-body strength as well as for prescribing the load during velocity-based resistance training routines. [ABSTRACT FROM AUTHOR]

This study aimed to compare the reliability and validity of the force-velocity (F-V) relationship parameters obtained from two-point methods differing in the distance between experimental points, and to evaluate the acute change in unloaded jump height after a vertical jump testing procedure based on multiple loads. Totally, 18 men randomly performed two sessions of the squat jump (SJ) and two sessions of the countermovement jump (CMJ) exercises against five external loads (17, 30, 45, 60 and 75 kg). The unloaded jump height was evaluated before and after each testing procedure. Five two-point methods (0–17, 0–30, 0–45, 0–60 and 0–75 kg) and the multiple-point method (0–17–30–45–60–75 kg) were used to model the F-V relationship. The most distant two-point method (0–75 kg) revealed a comparable reliability (CV< 12.1%; ICC> 0.72) and high concurrent validity (r > 0.91) with respect to the multiple-point method (CV< 10.9%; ICC> 0.72). The reliability and validity of the two-point methods decreased with the proximity of the applied loads. Unloaded jump height was significantly reduced after both testing procedures (p < 0.05). These results support the two-point method based on distant loads as a quick and less prone to fatigue procedure for testing the F-V relationship through vertical jumps. [ABSTRACT FROM AUTHOR]

This study aimed to compare the between-session reliability of three typically measured velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and maximum velocity [Vmax]) to assess vertical jump performance. Totally, 23 men had their squat jump (SJ) and countermovement jump (CMJ) tested against five different loading conditions (17, 30, 45, 60 and 75 kg) during two consecutive weeks. The two sessions of each jump type were performed within the same week separated by 48–72 h. The main finding was a significant difference in reliability between the variables, which were ranked from the highest to the lowest reliable as follows (median coefficient of variation [CV] and range): Vmax (CV = 2.35% [1.85%–3.23%]) >MV (CV = 3.29% [2.18%–4.40%]) >MPV (CV = 3.69% [2.08%–5.17%]). A significant variable × exercise interaction was also observed showing that the differences in reliability between the variables were meaningful during the SJ (MV: CV = 3.93% [3.06%–4.40%], MPV: CV = 4.61% [4.07%–5.17%], and Vmax: CV = 2.14% [1.85%–2.71%]), while no significant differences were observed for the CMJ (MV: CV = 2.43% [2.18%–3.70%], MPV: CV = 2.71% [2.08%–3.63%], and Vmax: CV = 2.40% [1.97%–3.23%]). These results suggest that the Vmax should be the recommended variable for obtaining a reproducible measure of lower-body ballistic performance, especially during the SJ exercise. [ABSTRACT FROM AUTHOR]

This study aimed to determine the suitability of the load-velocity relationship to prescribe the relative load (%1RM) in women, as well as to compare the load-velocity profile between sexes and participants with different strength levels. The load-velocity relationship of 14 men (1RM: 1.17 ± 0.19) and 14 women (1RM: 0.66 ± 0.13) were evaluated in the bench press exercise. The main findings revealed that: (I) the load-velocity relationship was always strong and linear (R2 range: 0.987–0.993), (II) a steeper load-velocity profile was observed in men compared to women (Effect size [ES]: 1.09), with men showing higher velocities for light loads (ES: − 0.81 and − 0.40 for the y-intercept and 30%1RM, respectively), but women reporting higher velocities for the heavy loads (ES: 1.14 and 1.50 at 90%1RM and 100%1RM, respectively); and (III) while the slope of the load-velocity profile was moderately steeper for weak men compared to their strong counterpart (ES: 1.02), small differences were observed between strong and weak women (ES: − 0.39). While these results support the use of the individual load-velocity relationship to prescribe the %1RM in the bench press exercise for women, they also highlight the large disparities in their load-velocity profile compared to men. [ABSTRACT FROM AUTHOR]

This study aimed to examine the reliability of different power and velocity variables during the Smith machine bench press (BP) and bench press throw (BPT) exercises. Twenty-two healthy men conducted four testing sessions after a preliminary BP one-repetition maximum (1RM) test. In a counterbalanced order, participants performed two sessions of BP in one week and two sessions of BPT in another week. Mean propulsive power, peak power, mean propulsive velocity, and peak velocity at each tenth percentile (20-70% of 1RM) were recorded by a linear transducer. The within-participants coefficient of variation (CV) was higher for the load-power relationship compared to the load-velocity relationship in both the BP (5.3% vs. 4.1%; CV ratio = 1.29) and BPT (4.7% vs. 3.4%; CV ratio = 1.38). Mean propulsive variables showed lower reliability than peak variables in both the BP (5.4% vs. 4.0%, CV ratio = 1.35) and BPT (4.8% vs. 3.3%, CV ratio = 1.45). All variables were deemed reliable, with the peak velocity demonstrating the lowest within-participants CV. Based upon these findings, the peak velocity should be chosen for the accurate assessment of BP and BPT performance. [ABSTRACT FROM AUTHOR]