Time Course of Recovery From Different Velocity Loss Thresholds and Set Configurations During Full-Squat Training.

ABSTRACT: Cornejo-Daza, PJ, Villalba-Fernández, A, González-Badillo, JJ, and Pareja-Blanco, F. Time course of recovery from different velocity loss thresholds and set configurations during full-squat training. J Strength Cond Res 38(2): 221-227, 2024-The aims of the research were to examine the effects of (a) velocity loss (VL) thresholds and (b) set configuration, traditional or cluster, on time-course recovery. A randomized cross-over research design was conducted, in which 15 resistance-trained men performed 4 protocols consisting of 3 sets of 70% 1RM in full squat (SQ), differing in the VL incurred during the set assessed with a linear velocity transducer: (a) 20% (70-20), (b) 30% (70-30), (c) 40% (70-40), and in the set configuration (d) 20% of VL using a cluster methodology (70-CLU). Movement velocity against the load that elicited a 1 m·s -1 velocity at baseline measurements (V1-load) in SQ, countermovement jump (CMJ) height, and sprint time in 20 m (T20) were assessed at baseline (Pre) and postintervention (Post, 6 hour-Post, 24 hour-Post, and 48 hour-Post). The 70-20 protocol resulted in fewer total repetitions than the other protocols ( p = 0.001), whereas 70-CLU, 70-30, and 70-40 completed similar total repetitions. The 70-30 protocol significantly worsened T20 at 6 hours-Post, CMJ at 48 hours-Post, and V1-load at 6 hours-Post ( p < 0.05). The 70-40 protocol significantly impaired T20 at 6 hours-Post, and CMJ and V1-load at 24 hours-Post ( p < 0.05). No significant performance reductions were observed for 70-20 and 70-CLU at 6 hours-Post, 24 hours-Post, and 48 hours-Post. Protocols with higher VL resulted in more pronounced fatigue and a slower rate of recovery. Cluster sets (70-CLU) resulted in higher volume than protocols with a similar level of fatigue (70-20) and a quicker recovery than protocols with a similar volume (70-30 and 70-40).

Load-Time and Load-Speed Relationship in the Resisted Sled Sprint Exercise: What Independent Variable Most Accurately Determines the Relative Load?

ABSTRACT: Jiménez-Lozano, M, Yáñez-García, JM, Mora-Custodio, R, Valle-Salguero, A, Díez-Fernández, DM, Franco-Márquez, F, González-Badillo, JJ, and Rodríguez-Rosell, D. Load-time and load-speed relationship in the resisted sled sprint exercise: what independent variable most accurately determines the relative load? J Strength Cond Res 37(11): 2167-2177, 2023-The aims of this study were to analyze the load-speed and load-time relationships in the resisted sled sprint exercise using different variables as relative load and to estimate the decrement of speed sprint and the increase of sprint time across different loads. Thirty young healthy men performed a progressive loading test in the countermovement jump (CMJ) exercise to determinate the load that elicited a 2 m·s-1 peak velocity (PV2-load) and in the full squat exercise to obtain the 1 repetition maximum (1RM) value and the load that elicited a 1 m·s-1 mean velocity (V1-load). In addition, subjects performed a progressive loading test in the resisted sled sprint exercise, whereas time and instantaneous speed at 10 (T10 and V10) and 20 m (T20 and V20) were measured. The independent variables used were body mass (BM), 1RM and V1-load in the squat exercise, the PV2-Load in the loaded CMJ exercise, 1RM + BM, V1-Load + BM, and PV2-Load + BM. To analyze whether relationships were dependent on individual performance obtained in unloaded sprint, the total sample was divided into 3 subgroups: high performance (T20 < 3.00 s), medium performance (T20:3.00-3.12 s), and low performance (T20 > 3.12 seconds) groups. The independent variables showing the highest relationships with time and speed in 10 and 20 m were %BM, %BM + V1-load, and %BM + PV2-load. Statistically significant differences between performance groups in %DSS (decrease of sprint speed) and %IST (increase sprint time) in 20 m were found when %BM was used as relative load, whereas there were no significant differences between groups for %BM + PV2-load or %BM + V1-load. In conclusion, the use of %BM + PV2-load and %BM + V1-load should be considered as variables for monitoring the relative load in the resisted sled sprint exercise.

Movement Velocity as a Determinant of Actual Intensity in Resistance Exercise.

This study aimed to analyze the acute mechanical, metabolic and EMG response to five resistance exercise protocols (REP) in the full squat (SQ) exercise performed with two velocity conditions: maximal intended velocity (MaxV) vs. half-maximal velocity (HalfV). Eleven resistance-trained men performed 10 REP (5 with each velocity conditions) in random order (72-96 h apart). The REP consisted of three sets of 8-3 repetitions against 45-65% 1RM. The percent change in countermovement jump (CMJ) height, velocity attained with the load that elicited a ~1.00 m·s-1 (V1-load), surface EMG variables and blood lactate concentration were assessed pre- vs. post-exercise protocols. MaxV resulted in greater percent changes (Δ: 12-25%) and intra-condition effect sizes (ES: 0.76-4.84) in loss of V1-load and CMJ height compared to HalfV (Δ: 10-16%; ES: 0.65-3.90) following all REP. In addition, MaxV showed higher post-exercise lactate concentration than HalfV (ES: 0.46-0.83; p<0.05). For EMG variables, only the Dimitrov index resulted in relevant changes after each REP, with MaxV showing greater magnitude of changes (23-38%) than HalfV (12-25%) across all REP. These results suggest that voluntary movement velocity is a key aspect to consider since it clearly determines the overall training intensity during resistance exercise.

Changes in Muscle Strength, Jump, and Sprint Performance in Young Elite Basketball Players: The Impact of Combined High-Speed Resistance Training and Plyometrics.

ABSTRACT: Yáñez-García, JM, Rodríguez-Rosell, D, Mora-Custodio, R, and González-Badillo, JJ. Changes in muscle strength, jump, and sprint performance in young elite basketball players: the impact of combined high-speed resistance training and plyometrics. J Strength Cond Res 36(2): 478-485, 2022-This study aimed to compare the effect of a combined resistance training (RT) and plyometrics on strength, sprint, and jump performance in basketball players of different ages. Thirty three elite basketball players from the same academy were categorized into 3 groups by chronological age: under-13 (U13, n = 11); under-15 (U15, n = 11); and under-17 (U17, n = 11). Players participated in a 6-week strength training program that included 2 sessions each week and consisted of full squats with low loads (45-60% 1 repetition maximum) and low volume (2-3 sets and 4-8 repetitions), jumps, and sprint exercises. All repetitions were performed at maximal intended velocity. In addition to strength training sessions, subjects performed 4 on court basketball training sessions plus 2 official matches per week. After training program, all 3 experimental groups resulted in significant improvements (p < 0.05-0.001) in maximal strength (Δ: 9.2-27.3%; effect size [ES]: 0.38-0.82), countermovement jump height (Δ: 6.6-11.6%; ES: 0.37-0.95), and sprint time in 10 and 20 m (Δ: -3.9 to -0.3%; ES: 0.09-0.69) for all experimental groups. Comparison between groups showed that training program was more effective in inducing improvements in most variables assessed for U13 compared with U15 (ES: 0.11-0.42) and U17 (ES: 0.20-0.43), whereas differences between U15 and U17 were relevant in jump and strength parameters (ES: 0.20-0.35). Therefore, these findings suggest that high-speed RT combined with plyometrics produces increments in several important variables, including strength, jump, and sprint, to yield high performance during a match in young basketball players. However, training program used seems to be generally less effective as the age of the basketball players increased.

Effect of velocity loss during squat training on neuromuscular performance.

This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in strength, vertical jump, sprint performance, and EMG variables. Thirty-three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity-based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55-70% 1RM), frequency (2 sessions/week), number of sets (3), and inter-set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre- and post-training. All groups showed significant (VL10%: 6.4-58.6%; VL30%: 4.5-66.2%; VL45%: 1.8-52.1%; p < 0.05-0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: -2.4%; VL30%: -1.8%; and VL45%: -0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55-70% 1RM characterized by a low-velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports-related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.

Mechanical and Metabolic Responses during High-intensity Training in Elite 800-m Runners.

The purpose of this study was to describe the mechanical and metabolic responses of a typical high-intensity training session in high-level 800-m athletes. Nine male high-level 800-m athletes (personal best 1:43-1:56 min:ss) performed a typical high-intensity interval training session consisting of 5×200 m with 4 min rest. Countermovement jump and blood lactate were measured at rest and after each running bout. Running times, ground contact times, and stride length were also measured. Running times and lactate (p<0.01) progressively increased from the first to the last running bout. Jump height (p<0.01) and stride length (p<0.05) progressively decreased from the first running bout to the last. A significant negative relationship (p<0.001; r =-0.83) was found between the individual values of jumping height and blood lactate concentration; and a significant positive relationship (p<0.01; r=0.67) was observed between the time in the 200 m and the contact times. In conclusion, the results demonstrated that the typical training session performed by 800-m athletes produced a high level of fatigue as evidenced by significant alterations in the mechanical and metabolic response. The impairments observed in the mechanical and metabolic parameters may indirectly reflect a state of energy deficit of the muscle contractile machinery and a reduction of the force-generating capacity.

Effects of Resistance Training on Physical Performance in High-Level 800-Meter Athletes: A Comparison Between High-Speed Resistance Training and Circuit Training.

ABSTRACT: Bachero-Mena, B, Pareja-Blanco, F, and González-Badillo, JJ. Effects of resistance training on physical performance in high-level 800-meter athletes: a comparison between high-speed resistance training and circuit training. J Strength Cond Res 35(7): 1905-1915, 2021-This study compared the effects of 2 resistance training programs during 25 weeks on physical performance and hormonal response in high-level 800 m athletes. Thirteen male athletes (800-m personal best: 1:43-1:58 minutes:ss) were divided into 2 groups: high-speed resistance training group (RTG) (n = 6) and circuit training group (CTG) (n = 7). Three tests (T1, T2, and T3) including sprint and 800 m running, strength exercises, and blood hormones samples were performed. Both groups showed improvements in 800 m performance (RTG: likely positive, 80/20/0%; CTG: very likely positive, 98/2/0%); however, RTG showed an additional improvement in 200 m (likely positive, 85/15/0%), countermovement jump (CMJ) (very likely positive, 98/2/0%), and squat (likely positive, 91/9/0%), whereas CTG reached likely positive (88/11/1%) effects in CMJ and unclear/possibly negative effects in the rest of the strength variables analyzed. Concerning hormones, RTG resulted in a likely increase (83/15/3%) in testosterone from T1 to T3, and CTG showed a likely increase (79/17/4%) in cortisol from T2 to T3, remaining the rest of the hormones analyzed unclear. These results suggest that a resistance training characterized by high-speed and low-volume produced better improvements in both strength and running performance than a circuit training, accompanied by little changes in the hormonal response.

Effects of Velocity Loss During Body Mass Prone-Grip Pull-up Training on Strength and Endurance Performance.

Sánchez-Moreno, M, Cornejo-Daza, PJ, González-Badillo, JJ, and Pareja-Blanco, F. Effects of velocity loss during body mass prone-grip pull-up training on strength and endurance performance. J Strength Cond Res 34(4): 911-917, 2020-This study aimed to analyze the effects of 2 pull-up (PU) training programs that differed in the magnitude of repetition velocity loss allowed in each set (25% velocity loss "VL25" vs. 50% velocity loss "VL50") on PU performance. Twenty-nine strength-trained men (age = 26.1 ± 6.3 years, body mass [BM] = 74.2 ± 6.4 kg, and 15.9 ± 4.9 PU repetitions to failure) were randomly assigned to 2 groups: VL25 (n = 15) or VL50 (n = 14) and followed an 8-week (16 sessions) velocity-based BM prone-grip PU training program. Mean propulsive velocity (MPV) was monitored in all repetitions. Assessments performed at pre-training and post-training included estimated 1 repetition maximum; average MPV attained with all common external loads used during pre-training and post-training testing (AVinc); peak MPV lifting one's own BM (MPVbest); maximum number of repetitions to failure lifting one's own BM (MNR); and average MPV corresponding to the same number of repetitions lifting one's own BM performed during pre-training testing (AVMNR). VL25 attained significantly greater gains than VL50 in all analyzed variables except in MNR (P < 0.05). In addition, VL25 improved significantly (P < 0.001) in all the evaluated variables while VL50 remained unchanged. In conclusion, our results suggest that once a 25% velocity loss is achieved during PU training, further repetitions did not elicit additional gains and can even blunt the improvement in strength and endurance performance.

Role of the Effort Index in Predicting Neuromuscular Fatigue During Resistance Exercises.

Rodríguez-Rosell, D, Yáñez-García, JM, Mora-Custodio, R, Torres-Torrelo, J, Ribas-Serna, J, and González-Badillo, JJ. Role of the effort index in predicting neuromuscular fatigue during resistance exercises. J Strength Cond Res XX(X): 000-000, 2020-This study aimed: (a) to analyze the acute mechanical, metabolic, and electromyographic (EMG) response to 16 resistance exercise protocols (REPs) defined by the first repetition's mean velocity and the percentage of velocity loss (%VL) over the set in the full-squat (SQ) exercise; and (b) to assess whether the effort index (EI, the product of the first repetition's mean velocity and the %VL in the set) could be used as an objective indicator of neuromuscular fatigue. Eleven resistance-trained men performed 16 REPs in the SQ exercise. For the configuration of the 16 REPs, 4 relative intensities (50, 60, 70, and 80% 1 repetition maximum) and 4 magnitudes of %VL (∼10, ∼20, ∼30, and ∼45%) were used. The induced fatigue after each REP was quantified using the percentage of change in (a) countermovement jump (CMJ) height, (b) mean propulsive velocity attained with the load that elicited an ∼1.00 m·s (V1 m·s load), and (c) changes in surface EMG variables. Blood lactate concentration was also collected. The EI presented very strong relationships with the %VL with the V1 m·s load, CMJ height, and post-exercise lactate concentration (r = 0.92, 0.93, and 0.91, respectively; p < 0.001). Moderate to strong relationships were found between the EI and the changes in amplitude (r = 054-0.58; p < 0.05), frequency (r = -0.55 to -0.83; p < 0.05-0.001), and time-frequency (r = 0.52-0.77; p < 0.05-0.001) EMG variables. In addition, the moderate to strong relationships found between the relative changes in mechanical, metabolic, and EMG variables after each REP reinforce the validity of the EI as an objective indicator of muscle fatigue, metabolic stress, and neural effect induced by typical resistance training sessions. Thus, by adjusting the EI in each session, it is possible to quantifying the actual level of effort experienced by each individual during resistance exercises.

Relationship Between Velocity Loss and Repetitions in Reserve in the Bench Press and Back Squat Exercises.

Rodríguez-Rosell, D, Yáñez-García, JM, Sánchez-Medina, L, Mora-Custodio, R, and González-Badillo, JJ. Relationship between velocity loss and repetitions in reserve in the bench press and back squat exercises. J Strength Cond Res 34(9): 2537-2547, 2020-This study aimed to compare the pattern of repetition velocity decline during a single set to failure performed against 4 relative loads in the bench press (BP) and full back squat (SQ) exercises. After an initial test to determine 1 repetition maximum (1RM) strength and load-velocity relationships, 20 men performed one set of repetitions to failure (MNR test) against loads of 50, 60, 70, and 80% 1RM in BP and SQ, on 8 random order sessions performed every 6-7 days. Velocity against the load that elicited a ∼1.00 m·s (V1 m·s load) was measured before and immediately after each MNR test, and it was considered a measure of acute muscle fatigue. The number of repetitions completed against each relative load showed high interindividual variability in both BP (coefficient of variation [CV]: 15-22%) and SQ (CV: 26-34%). Strong relationships were found between the relative loss of velocity in the set and the percentage of performed repetitions in both exercises (R = 0.97 and 0.93 for BP and SQ, respectively). Equations to predict repetitions left in reserve from velocity loss are provided. For a given magnitude of velocity loss within the set (15-65%), the percentages of performed repetitions were lower for the BP compared with the SQ for all loads analyzed. Acute fatigue after each set to failure was found dependent on the magnitude of velocity loss (r = 0.97 and 0.99 for BP and SQ, respectively) but independent of the number of repetitions completed by each participant (p > 0.05) for both exercises. The percentage of velocity loss against the V1 m·s load decreased as relative load increased, being greater for BP than SQ. These findings indicate that monitoring repetition velocity can be used to provide a very good estimate of the number (or percentage) of repetitions actually performed and those left in reserve in each exercise set, and thus to more objectively quantify the level of effort incurred during resistance training.

Time Course of Recovery From Resistance Exercise With Different Set Configurations.

Pareja-Blanco, F, Rodríguez-Rosell, D, Aagaard, P, Sánchez-Medina, L, Ribas-Serna, J, Mora-Custodio, R, Otero-Esquina, C, Yáñez-García, JM, and González-Badillo, JJ. Time course of recovery from resistance exercise with different set configurations. J Strength Cond Res 34(10): 2867-2876, 2020-This study analyzed the response to 10 resistance exercise protocols differing in the number of repetitions performed in each set (R) with respect to the maximum predicted number (P). Ten males performed 10 protocols (R(P): 6(12), 12(12), 5(10), 10(10), 4(8), 8(8), 3(6), 6(6), 2(4), and 4(4)). Three sets with 5-minute interset rests were performed in each protocol in bench press and squat. Mechanical muscle function (countermovement jump height and velocity against a 1 m·s load, V1-load) and biochemical plasma profile (testosterone, cortisol, growth hormone, prolactin, IGF-1, and creatine kinase) were assessed at several time points from 24-hour pre-exercise to 48-hour post-exercise. Protocols to failure, especially those in which the number of repetitions performed was high, resulted in larger reductions in mechanical muscle function, which remained reduced up to 48-hour post-exercise. Protocols to failure also showed greater increments in plasma growth hormone, IGF-1, prolactin, and creatine kinase concentrations. In conclusion, resistance exercise to failure resulted in greater fatigue accumulation and slower rates of neuromuscular recovery, as well as higher hormonal responses and greater muscle damage, especially when the maximal number of repetitions in the set was high.

Jump height loss as an indicator of fatigue during sprint training.

This study analysed the acute mechanical and metabolic responses to a sprint training session focused on maintaining maximal speed until a given speed loss was reached. Nine male high-level sprinters performed 60 m running sprints up to a 3% in speed loss with 6 min rests between sets. Mechanical responses (countermovement jump (CMJ) height and speed loss) and metabolic responses (blood lactate and ammonia concentrations) were measured pre-exercise and after each set was performed. Jump height loss showed almost perfect relationships with both lactate (r = 0.91) and ammonia (r = 0.91) concentrations. In addition, nearly perfect relationships were observed for each athlete between CMJ height loss and lactate (r = 0.93-0.99) and ammonia (r = 0.94-0.99). Very large correlations were found between speed loss and lactate (r = 0.83), and ammonia (r = 0.86) concentrations. Furthermore, close relationships were observed for each athlete between speed loss and lactate (r = 0.86-0.99), and ammonia (r = 0.88-0.98). These results suggest that the CMJ test may allow more accurate setting of training loads in sprint training sessions, by using an individualised sprint dose based on mechanical and physiological responses rather than a standard fixed number of sprints for all athletes.

Velocity- and power-load relationships in the half, parallel and full back squat.

This study aimed to compare the load-velocity and load-power relationships of three common variations of the squat exercise. 52 strength-trained males performed a progressive loading test up to the one-repetition maximum (1RM) in the full (F-SQ), parallel (P-SQ) and half (H-SQ) squat, conducted in random order on separate days. Bar velocity and vertical force were measured by means of a linear velocity transducer time-synchronized with a force platform. The relative load that maximized power output (Pmax) was analyzed using three outcome measures: mean concentric (MP), mean propulsive (MPP) and peak power (PP), while also including or excluding body mass in force calculations. 1RM was significantly different between exercises. Load-velocity and load-power relationships were significantly different between the F-SQ, P-SQ and H-SQ variations. Close relationships (R2 = 0.92-0.96) between load (%1RM) and bar velocity were found and they were specific for each squat variation, with faster velocities the greater the squat depth. Unlike the F-SQ and P-SQ, no sticking region was observed for the H-SQ when lifting high loads. The Pmax corresponded to a broad load range and was greatly influenced by how force output is calculated (including or excluding body mass) as well as the exact outcome variable used (MP, MPP, PP).

Movement Velocity as a Measure of Level of Effort During Resistance Exercise.

Morán-Navarro, R, Martínez-Cava, A, Sánchez-Medina, L, Mora-Rodríguez, R, González-Badillo, JJ, and Pallarés, JG. Movement velocity as a measure of level of effort during resistance exercise. J Strength Cond Res 33(6): 1496-1504, 2019-This study analyzed whether the loss of repetition velocity during a resistance exercise set was a reliable indicator of the number of repetitions left in reserve. After the assessment of one-repetition (1RM) strength and full load-velocity relationship, 30 men were divided into 3 groups according to their 1RM strength per body mass: novice, well trained, and highly trained. On 2 separate occasions and in random order, subjects performed tests of maximal number of repetitions to failure against loads of 65, 75, and 85% 1RM in 4 exercises: bench press, full squat, prone bench pull, and shoulder press. For each exercise, and regardless of the load being used, the absolute velocities associated with stopping a set before failure, leaving a certain number of repetitions (2, 4, 6, or 8) in reserve, were very similar and showed a high reliability (coefficient of variation [CV] 4.4-8.0%). No significant differences in these stopping velocities were observed for any resistance training exercise analyzed between the novice, well trained and highly trained groups. These results indicate that by monitoring repetition velocity one can estimate with high accuracy the proximity of muscle failure and, therefore, to more objectively quantify the level of effort and fatigue being incurred during resistance training. This method emerges as a substantial improvement over the use of perceived exertion to gauge the number of repetitions left in reserve.

Range of Motion and Sticking Region Effects on the Bench Press Load-Velocity Relationship.

This study aimed to analyze the influence of range of motion (ROM) on main biomechanical parameters of the bench press (BP) exercise: i) load-velocity relationship by mean (MV) and mean propulsive velocity (MPV), ii) one-repetition maximum strength (1RM); iii) contribution of the propulsive and braking phases, and iv) presence of the sticking region key parameters (first peak barbell velocity: Vmax1, minimum velocity: Vmin and second peak barbell velocity: Vmax2). Forty-two strength-trained males performed a progressive loading test, starting at 20 kg and gradually increasing the load in 10 kg until MPV ≤ 0.50 m·s-1 and 5 down to 2.5 kg until 1RM, in three different ROMs: full ROM (BPFULL), two-thirds (BP2/3) and one-third (BP1/3). While significant differences were detected in the velocity attained against loads between 30-95% 1RM (BPFULL, BP2/3 and BP1/3, p < 0.05), both MV and MPV showed a very close relationship to %1RM for the three BP variations (R2 = 0.935-0.966). The contribution of the braking phase decreased progressively until it completely disappeared at the 80%, 95% and 100% 1RM loads in BP1/3, BP2/3 and BPFULL, respectively. The 1RM increased as the ROM decreased (BPFULL < BP2/3 < BP1/3, p < 0.05). Despite the three biomechanical parameters that define the sticking region on the velocity-time curves were only observed in BPFULL variation, in 54.5% of the cases the subjects started their BP2/3 displacement before reaching the position at which the Vmin occurs in their BPFULL exercise. The complete or partial presence of the sticking region during the concentric action of the lift seems to underlie the differences in the 1RM strength, load-velocity profiles and the contribution of the propulsive phase in the BP exercise at different ROMs.

Effects of Resistance Training and Combined Training Program on Repeated Sprint Ability in Futsal Players.

The purpose of this study was to compare the effects of 6 weeks resistance training (RT) with combined RT and loaded change of direction (CD) exercise on muscle strength and repeated sprint ability (RSA) in futsal players. Thirty-four players (age: 23.7±4.1 years; height: 1.77±0.06 m; body mass: 74.1±8.2 kg) were randomly assigned into three groups: full squat group (SG, n=12), combined full squat and CD group (S+CDG, n=12), and control group (CG, n=10). The RT for SG consisted of full squat with low-load (~45-60% 1RM) and low-volume (2-3 sets and 4-6 repetitions), whereas the S+CDG performed the same RT program combined with loaded CD (2-5 sets of 10 s). Estimated one-repetition maximum (1RMest) and variables derived from RSA test including mean sprint time (RSAmean), best sprint time (RSAbest), percent sprint decrement (Sdec), mean ground contact time (GCTmean) and mean step length (SL) were selected as testing variables. Changes in sprint time and GCT in each sprint were also analysed. Both experimental groups showed significant (P<0.05-0.001) improvements for 1RMest, RSAbest and first and second sprint time. In addition, S+CDG achieved significant (P<0.05-0.001) improvements in RSAmean, sprint time (from fifth to ninth sprint) and GCT (from third to eighth sprint). These results indicate that only 6 weeks of low-load and low-volume RT combined with CD in addition to routine futsal training is enough to improve RSA and strength performance simultaneously in futsal players.

Effect of different inter-repetition rest intervals across four load intensities on velocity loss and blood lactate concentration during full squat exercise.

This study aimed to analyze the acute effect of inter-repetition rest (IRR) intervals on mechanical and metabolic response during four resistance exercise protocols (REPs). Thirty resistance-trained men were randomly assigned to: continuous repetitions (CR), 10 s (IRR10) or 20 s (IRR20) inter-repetition rest. The REPs consisted of 3 sets of 6, 5, 4 and 3 repetitions against 60, 70, 75 and 80% 1RM, respectively, in the full squat exercise. Muscle fatigue was assessed using: percentage of velocity loss over three sets, percentage of velocity loss against the ~1 m·s-1 load (V1 m·s-1), and loss of countermovement jump (CMJ) height pre-post exercise. Blood lactate was measured before and after exercise. The percentage of velocity loss over three sets and lactate concentration were significantly lower (P < 0.05) for IRR groups compared to CR in all REPs. The CR group showed a significantly higher (P < 0.05) velocity loss against V1 m·s-1 load and loss of CMJ height pre-post exercise than IRR groups in REP against 60% 1RM. In conclusion, both IRR groups produced a significant lower degree of fatigue compared to CR group. However, no significant differences were found in any measured variables between IRR configurations.

Time course of recovery following resistance training leading or not to failure.

PURPOSE: To describe the acute and delayed time course of recovery following resistance training (RT) protocols differing in the number of repetitions (R) performed in each set (S) out of the maximum possible number (P). METHODS: Ten resistance-trained men undertook three RT protocols [S × R(P)]: (1) 3 × 5(10), (2) 6 × 5(10), and (3) 3 × 10(10) in the bench press (BP) and full squat (SQ) exercises. Selected mechanical and biochemical variables were assessed at seven time points (from - 12 h to + 72 h post-exercise). Countermovement jump height (CMJ) and movement velocity against the load that elicited a 1 m s-1 mean propulsive velocity (V1) and 75% 1RM in the BP and SQ were used as mechanical indicators of neuromuscular performance. RESULTS: Training to muscle failure in each set [3 × 10(10)], even when compared to completing the same total exercise volume [6 × 5(10)], resulted in a significantly higher acute decline of CMJ and velocity against the V1 and 75% 1RM loads in both BP and SQ. In contrast, recovery from the 3 × 5(10) and 6 × 5(10) protocols was significantly faster between 24 and 48 h post-exercise compared to 3 × 10(10). Markers of acute (ammonia, growth hormone) and delayed (creatine kinase) fatigue showed a markedly different course of recovery between protocols, suggesting that training to failure slows down recovery up to 24-48 h post-exercise. CONCLUSIONS: RT leading to failure considerably increases the time needed for the recovery of neuromuscular function and metabolic and hormonal homeostasis. Avoiding failure would allow athletes to be in a better neuromuscular condition to undertake a new training session or competition in a shorter period of time.

Velocity Loss as a Variable for Monitoring Resistance Exercise.

This study aimed to analyze: 1) the pattern of repetition velocity decline during a single set to failure against different submaximal loads (50-85% 1RM) in the bench press exercise; and 2) the reliability of the percentage of performed repetitions, with respect to the maximum possible number that can be completed, when different magnitudes of velocity loss have been reached within each set. Twenty-two men performed 8 tests of maximum number of repetitions (MNR) against loads of 50-55-60-65-70-75-80-85% 1RM, in random order, every 6-7 days. Another 28 men performed 2 separate MNR tests against 60% 1RM. A very close relationship was found between the relative loss of velocity in a set and the percentage of performed repetitions. This relationship was very similar for all loads, but particularly for 50-70% 1RM, even though the number of repetitions completed at each load was significantly different. Moreover, the percentage of performed repetitions for a given velocity loss showed a high absolute reliability. Equations to predict the percentage of performed repetitions from relative velocity loss are provided. By monitoring repetition velocity and using these equations, one can estimate, with considerable precision, how many repetitions are left in reserve in a bench press exercise set.

Light-load maximal lifting velocity full squat training program improves important physical and skill characteristics in futsal players.

This study aimed to compare the effect of 6 weeks of resistance training or combined resistance training and change of direction exercises on physical performance and motor skills in futsal players. Thirty-four futsal players were divided into full squat group (SG, n = 12), combined full squat and change of direction exercises group (S+CDG, n = 12) and control group (CG, n = 10). The resistance training for SG consisted of full squat with low load (~45-58% 1RM) and low volume (4-6 repetitions), whereas the S+CDG performed the same resistance training program combined with loaded change of direction. Sprint time in 10 and 20 m, change of direction test, countermovement vertical jump (CMJ) height, maximal strength and force-velocity relationship in full squat exercise, kicking speed ball (BSmean) and repeated sprint ability (RSAmean) were selected as testing variables. Both experimental groups showed significant improvements for CMJ, BSmean and all strength parameters. Only SG resulted in significant sprint gains, whereas S+CDG also achieved significant improvements in RSAmean. The CG remained unchanged after training period. No significant differences were found between both experimental groups. These findings suggest that only 12 sessions of either lightweight resistance training alone, lifting the load at maximal intended velocity or combined with change of direction exercises is enough to improve several physical and skills capacities critical to futsal performance in adult players.