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This study examined the acute effects of dynamic stretching at different velocities on the neuromuscular system. Fourteen participants underwent four experimental sessions in random order: (1) control (lying at rest with the ankle in a neutral position); (2) slow velocity dynamic stretching (50 beats/min; SLOW DS ); (3) moderate velocity dynamic stretching (70 beats/min; MOD DS ); and (4) fast velocity dynamic stretching (90 beats/min; FAST DS ). The stretching protocols consisted of four sets of 10 repetitions and targeted the plantar flexor muscles of the right ankle. Assessments included corticospinal excitability (via motor-evoked potential-MEP/M max ), spinal reflex activity (via H-reflex-H max /M max ), muscle contractile properties (peak twitch torque; PTT), maximal voluntary contraction (MVC), and maximal range of motion (ROM max ). Dynamic stretching did not affect MEP/M max and MVC of the plantar flexor muscles (P > 0.05). All stretching protocols similarly reduced soleus H max /M max (P < 0.05), and increased PTT (P < 0.05). Additionally, all conditions, including control, similarly increase ROM max (P < 0.05, and Cohen's d value of -0.39, -0.28, -0.38 and -0.29 for CON, SLOW DS , MOD DS and FAST DS , respectively). Therefore, dynamic stretching reduces spinal reflex activity and enhances muscle contractile properties irrespective of movement velocity without impairing corticospinal excitability and MVC., (© 2024 The Author(s). Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

The purpose of the present study was to analyze the effects of the order of resistance training (RT) exercises on hypertrophy in young adult men. Thirty-six young adult men (age, 21.9 ± 2.5 years; body mass, 72.6 ± 12.1 kg, height, 176.9 ± 7.4 cm; body mass index, 23.1 ± 3.3 kg/m 2 ) were randomly assigned to 1 of 2 training groups that performed a 6-week RT program in either (i) a traditional approach starting with multi-joint (MJ) exercises followed by single-joint exercises (SJ) (MJ-SJ, n = 19) or (ii) in reverse order (SJ-MJ, n = 17). Muscle thickness of the biceps brachii and mid-thigh were assessed by ultrasound. Lean soft tissue (LST) was assessed by dual-energy X-ray absorptiometry. Both groups similarly increased (P < 0.05) biceps brachii thickness (MJ-SJ = +14.2%, SJ-MJ = +13.8%). Alternatively, only the MJ-SJ group presented an increase in mid-thigh thickness from pre- to post-training (MJ-SJ = +7.2%, SJ-MJ = +3.9%). Upper limb LSTs (MJ-SJ = +5.2%, SJ-MJ = +7.5%) were statistically similar between conditions, and a trend for significance (P = 0.07) was found for trunk LST (MJ-SJ = +7.2%, SJ-MJ = +1.7%). Nonsignificant pre- to post-training changes were observed for lower limb LSTs (MJ-SJ = +0.7%, SJ-MJ = +1.8%). Our data suggest that both sequences are effective for increasing muscle hypertrophy over a short-term RT period; there may be a potentially beneficial hypertrophic effect for the mid-thigh by performing exercises in a manner that progresses from MJ to SJ exercises.

Acute changes in muscle architecture influenced by muscle swelling might be associated with chronic adaptations to resistance exercise, including skeletal muscle growth. Concentric (CON) and eccentric (ECC) muscle actions both play a role in hypertrophic processes, but the influence of each on acute indices of muscle swelling (i.e., muscle thickness (MT) and pennation angle (PA)) remains relatively unknown. Therefore, this study compared the acute changes in MT and PA in response to work-matched CON versus ECC isokinetic exercise. Twelve university-aged students performed 2 bouts of maximal isokinetic knee extensions at 120°·s -1 on the same day: 50 CON followed by a work-matched ECC bout (∼5000 J; 28 ± 5 reps) with the contralateral limb. Ultrasound images were captured from the middle and distal sites of the vastus lateralis before and immediately after each exercise bout. From these images, MT and PA were measured. Middle and distal MT (11% and 14%, respectively; p < 0.001) and middle PA (39%, p < 0.001) increased only after CON. In addition, changes in MT were strongly related to the amount of total work performed (r = 0.76) during CON. Our results suggest that when the workload is matched between CON and ECC muscle actions performed at a moderate velocity, CON actions seem to be a more potent stimulus for inducing acute changes in MT and PA.

This was a placebo-controlled randomized study that aimed to investigate the effects of strength training (ST) combined with antioxidant supplementation on muscle performance and thickness. Forty-two women (age, 23.8 ± 2.7 years; body mass, 58.7 ± 11.0 kg; height, 1.63 ± 0.1 m) were allocated into 3 groups: vitamins (n = 15), placebo (n = 12), or control (n = 15). The vitamins and placebo groups underwent an ST program, twice a week, for 10 weeks. The vitamins group was supplemented with vitamins C (1 g/day) and E (400 IU/day) during the ST period. Before and after training, peak torque (PT) and total work (TW) were measured on an isokinetic dynamometer, and quadriceps muscle thickness (MT) was assessed by ultrasound. Mixed-factor ANOVA was used to analyze data and showed a significant group × time interaction for PT and TW. Both the vitamins (37.2 ± 5.4 to 40.3 ± 5.6 mm) and placebo (39.7 ± 5.2 to 42.5 ± 5.6 mm) groups increased MT after the intervention (P < 0.05) with no difference between them. The vitamins (146.0 ± 29.1 to 170.1 ± 30.3 N·m) and placebo (158.9 ± 22.4 to 182.7 ± 23.2 N·m) groups increased PT after training (P < 0.05) and PT was higher in the placebo compared with the control group (P = 0.01). The vitamins (2068.3 ± 401.2 to 2295.5 ± 426.8 J) and placebo (2165.1 ± 369.5 to 2480.8 ± 241.3 J) groups increased TW after training (P < 0.05) and TW was higher in the placebo compared with the control group (P = 0.01). Thus, chronic antioxidant supplementation may attenuate peak torque and total work improvement in young women after 10 weeks of ST.

The purpose of the present study was to evaluate the changes in movement velocity during resistance training with different loads while the trainees attempted to move the load at a predetermined repetition duration. Twenty-one resistance-trained men (age: 25.7 ± 5 years; height: 177.0 ± 7.2 cm; mass: 85.4 ± 13.56 kg) volunteered to participate in the study. Participants performed 2 test sessions. The first to determine 1-repetition maximum (1RM) load, and the second to evaluate velocity loss during a set to failure performed at 75% and 50% of 1RM using a 2-s concentric and 2-s eccentric repetition duration, controlled by a mobile app metronome. When using 75% 1RM there was a significant loss of movement velocity between the antepenultimate and the penultimate repetition (5.33%, p < 0.05), as well as during the penultimate and the last (22.11%, p < 0.05). At 50% of 1RM the participants performed the set until momentary failure without significant velocity loss. Monitoring velocity loss during high-load resistance training through simple methods can be an important tool for standardize the intensity of effort employed during submaximal training. This can be useful in clinical conditions where maximum exertions are contraindicated or when specific logistics are lacking.

Purpose: Preload of antagonist muscles can be achieved by reciprocal actions (RAs) or by opposing muscle actions. However, evidence concerning neuromuscular and fatigue responses are scarce., Objective: To compare the effects of different knee flexor (KF) preload methods on knee extension (KE) vastus medialis muscle fatigue, based on EMG-spectral index (FI), load range (LR), total work (TW), blood lactate (LAC) and biceps femoris co-activation (BFc) during resistance exercise., Methods: Twenty-four healthy men (23.5±3.6yrs) performed three antagonist pre-load isokinetic exercises (4 sets, 10 repetitions, 60°s(-1), 1min rest between sets): RA (KF contraction immediately followed by KE); Superset (SS; one KF set immediately followed by one KE set); Multiple Set (MS; four KF sets followed by four KE sets)., Results: Total work was significantly greater in RA. There was no significant decrease in LR between sets in RA. The BFc did not differ between protocols (p=0.063). However, RA presented greater biceps femoriscoactivation. The FI was greater during SS compared to RA and MS (p<0.05). The SS had greater LAC when compared to MS and RA (p=0.005 and p=0.007, respectively)., Conclusion: It is suggested that the RA protocol is more neuromuscular and metabolic efficient during the performance of knee extension resistance exercise., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The relationship between surface electromyography (SEMG) amplitude and the ventilatory threshold has been extensively studied. However, previous studies of muscle fiber conduction velocity (MFCV) are scarce and present insufficient evidence concerning the relationship between MFCV and metabolic responses during cycling. Based on that fact, the purpose of this study is twofold: (1) to investigate the existence of a MFCV threshold (MFCVT) during cycling and (2) to verify if this possible breakpoint is correlated with the ventilatory threshold (VT) and the SEMG threshold (SEMGT). Eight trained male cyclists (age 36.0±9.7years) performed an incremental cycling test with initial workload of 150W gradually incremented by 20Wmin(-1) until the exhaustion. Gas analyses were conducted using a breath-by-breath open-circuit spirometry and SEMG were registered from vastus lateralis in each pedaling cycle with a linear array of electrodes. A bi-segmental linear regression computer algorithm was used to estimate VT, MFCVT and SEMGT respectively in the carbon dioxide production (VCO2), MFCV and electromyography root mean square (EMG RMS) curves. The one way ANOVA for repeated measures did not reveal any significant difference among VT (77.1±7.5% of VO2max), MFCVT (80.3±10.4% of VO2max) and SEMGT (81.9±11.7% of VO2max). The Bland and Altman procedure confirmed a good concordance between SEMGT and VT (Bias=5.5 of %VO2max) as well as MFCVT and VT (Bias=5.2 of %VO2max). The present findings suggest that muscle fiber conduction velocity threshold is a valid and reliable non-invasive tool to obtain information about ventilatory threshold in trained cyclists., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: Previous studies have shown that preloading an antagonist muscle may increase the acute agonist neuromuscular performance. In addition, studies have suggested that very short-term resistance exercise (RE) programs may also be useful to increase strength and muscular performance., Objectives: To evaluate the effects of three days of RE using a reciprocal action method on the muscular performance of healthy men and to compare these effects with those of a traditional RE group., Method: Thirty-three men (21.1 ± 2.3 years) were randomly assigned to one of three groups: 1) reciprocal (REC; knee flexion immediately followed by a knee extension exercise); 2) traditional (TRA; non-preload; a concentric knee extension exercise); and 3) control (CON; no exercise). The REC and TRA subjects performed four sets of 10 repetitions at 60º/s with one minute of rest. The pre- and post-RE tests included two sets of four maximal concentric repetitions at 60º/s and 180º/s. A 3x2 ANOVA with Tukey post-hoc was used to analyze the differences in peak torque (PT), rating of acceleration development (RAD) and time to peak torque (TIMEtorque)., Results: A significant PT increase was found for REC and TRA (p<0.05) at 60º/s and for REC at 180º/s (p<0.05). There was a decrease in the RAD for REC and TRA (p<0.05), and TIMEtorque showed a significant decrease for REC. The inter-group analysis revealed that REC is more effective than TRA for PT gains at both velocities (p<0.05)., Conclusion: It is recommended that REC offers benefits for the clinical practice of professionals involved in neuromuscular rehabilitation.

Background: Pre-activation of antagonistic muscles is used in different modalities of exercise and neuromuscular rehabilitation protocols, but its effectiveness is still controversial., Objective: To verify the impact of two different methods of pre-activation of knee antagonist muscles in the neuromuscular performance and electromyographic activity of knee extensors., Methods: Fifteen healthy men (23.9±4.2 years of age, 1.78±0.08 meters and 81.4±10.7 kg) performed, on different days, two protocols of isokinetic muscle contraction with 4 sets of 10 repetitions at 60°.s-1 and 1 minute between sets: (1) Reciprocal Contraction (RC): reciprocal concentric exercise of agonist/antagonist muscles (knee flexion [KF] immediately followed by knee extension [KE]) and (2) Superset (SS): alternated concentric exercise of agonist/antagonist muscles (KF set followed by a set of KE). A repeated measures ANOVA with least-significant difference post-hoc test was used to detect differences between protocols., Results: There were no significant differences between protocols (p>0.05) for peak torque (PT) and total work (Tw). On the SS protocol there was a significant decrease in Tw on the last two sets (p<0.05) while for RC the decrease occurred only in the last set. There were no significant differences of root mean square (RMS) between protocols, but the activation pattern was more uniform during the RC protocol., Conclusion: The results indicated that the peak torque was not influenced by the different pre-activation methods. However, the RC protocol appears to better maintain the total work training volume.

The aim of this study was to evaluate and compare acute effects of a reciprocal action protocol and a super-set protocol on knee extensor performance during concentric isokinetic exercise. Fourteen men aged 29.4 ± 6.1 years were tested on three different protocols, with 1 min of rest between sets: control (3 sets of 10 isokinetic knee extension repetitions), reciprocal action protocol (3 sets of 10 repetitions of reciprocal isokinetic concentric knee flexion and knee extension repetitions), and super-set protocol (3 sets of a combination of 10 repetitions of knee flexion immediately followed by 10 repetitions of knee extension repetitions). Tests were performed at 60° · s(-1) and 180° · s(-1), randomized across 3 days and separated by at least 72 h. There were no significant differences between protocols for peak torque at 60° · s(-1) or 180° · s(-1). Total work was significantly higher during the reciprocal action protocol compared with the super-set protocol at 60° · s(-1). There was a significant decline in peak torque (from 240.6 to 212.9 N · m) and total work (from 2294 to 1899 J) for the control condition at 60° · s(-1). Also, total work declined significantly across sets for the super-set protocol at 60° · s(-1) (from 2157 to 1707 J). Results indicate that a reciprocal action protocol provides torque maintenance during multiple sets of isokinetic training, both at slow and high velocities.

The purpose of this study was to examine the effect of two between set rest intervals (RI) on isokinetic knee extension peak torque (PT) produced by sedentary women and men. Seventeen young women (27.18 ± 4.05 yrs) and 16 young men (26.75 ± 4.73 yrs) performed 3 sets of 10 unilateral isokinetic knee extension at 60° and 180°/s. The RI between sets was 60 and 120 s, counterbalanced across 2 testing days. Statistical evaluation of the data was performed using a 3-way mixed factor ANOVA (gender x rest interval x sets). Males and females exhibited decreases (p<0.05) in PT with 120 s RI at 60°/s. There was no significant decline in PT in the female group during both RI at 180°/s. Men showed a significant decrease in PT only with 60 s RI. Young women and men require more than 120 s of RI to recover full PT at 60°/s. However, full quadriceps's muscle strength recovery can be attained with a 60 and 120 s at 180°/s in women, but in men only with a 120 s at the same velocity., (© Georg Thieme Verlag KG Stuttgart · New York.)

The present study investigates the behavior of action potential conduction velocity (CV) on each repetition of an isokinetic test set and on each set as a whole. A total of seven healthy men (27.7 ± 2.8 yrs, 1.74 ± 0.06 m, and 79.6 ± 11.0 Kg) performed 3 (three) sets of 10 (ten) maximal concentric repetitions of dominant knee extension at 60°/s on an isokinetic dynamometer, with 1 minute of rest interval between the sets. The surface electromyographic (SEMG) signals were recorded from the vastus lateralis muscle during the exercises. CV was estimated with a spectral matching method which requires the SEMG acquisition technique based on a flexible linear array of electrodes (here used with 8 electrodes and 5 mm inter-electrode distance). With the view to minimize the factors other than fatigue that also influence the CV behavior, only the extension phase of the isokinetic exercise repetition was considered for measurements. Results showed that CV usually increases during a single repetition whereas it has a decreasing tendency along the isokinetic set seen as a whole.

The purpose of this study was to compare the effect of two different rest intervals between sets of isokinetic knee extension exercise on peak torque (PT), and Total Work (TW) between untrained younger and older men. Seventeen young men (24.22+/-2.58 yrs) and 20 older men (66.85+/-4.02 yrs) performed 3 sets of 10 unilateral isokinetic knee extension repetitions at 60 degrees /s. The rest intervals between sets were 1 and 2 min. There was a significant decline in PT when 1 and 2 min rest intervals were used for young men, but not when a 2 min rest interval was applied for old men. There was also a significant decline in TW among the 3 sets when 1 and 2 min rest intervals were applied for young men, whereas the decline in TW in older men occurred only between the 2(nd) and 3(rd) sets. PT and TW in the 3(rd) set were significant greater following a 2 min rest interval than a 1 min rest in both young and older men. The present study indicated that non-resistance trained young men may require longer rest interval to recover full PT and TW when compared to older men., (Georg Thieme Verlag KG Stuttgart, New York.)

This study investigated the effect of a 10-week power training (PT) program versus traditional resistance training (TRT) on functional performance, and muscular power and strength in older men. Twenty inactive volunteers (60-76 years old) were randomly assigned to a PT group (three 8-10 repetition sets performed as fast a possible at 60% of 1-RM) or a TRT group (three 8-10 repetition sets with 2-3 s contractions at 60% of 1-RM). Both groups exercised 2 days/week with the same work output. Outcomes were measured with the Rikli and Jones functional fitness test and a bench and leg press test of maximal power and strength (1-RM). Significant differences between and within groups were analyzed using a two-way analysis of variance (ANOVA). At 10 weeks there was a significantly (P < 0.05) greater improvement in measures of functional performance in the PT group. Arm curling improved by 50 versus 3% and a 30 s chair-stand improved by 43 versus 6% in the PT and TRT groups, respectively. There was also a significantly greater improvement in muscular power (P < 0.05) in the PT group. The bench press improved by 37 versus 13%, and the leg press by 31 and 8% in the PT and TRT groups, respectively. There was no significant difference between groups in improved muscular strength. It appears that in older men there may be a significantly greater improvement in functional performance and muscular power with PT versus low velocity resistance training.

This study investigated the effects of 5 and 15 °C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5 x 20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5 °C; (2) 15 °C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h postexercise. There was no between-group difference in isometric strength recovery (p = 0.73). However, countermovement jump recovered quicker in cold-water immersion groups compared to control group (p < 0.05). Countermovement jump returned to baseline after 72 h in 15 °C, 5 °C group recovered after 96 h and control did not recovered at any time point measured. Also, creatine kinase returned to baseline at 72 h and remained stable for all remaining measurements for 15 °C group, whereas remained elevated past 168 h in both 5 °C and control groups. There was a trend toward lower muscle soreness (p = 0.06) in 15 °C group compared to control at 24 h post-exercise. The result suggests that cold-water immersion promote recovery of stretch-shortening cycle performance, but not influence the recovery of maximal contractile force. Immersion at warmer temperature may be more effective than colder temperatures promoting recovery from strenuous exercise. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the acute effect of 2 different resting intervals (RI) between sets of isokinetic knee extension exercise on peak torque (PT) and total work (TW) in breast cancer survivors (BCS) and control group (CNT). 16 BCS (52 ± 4 years) and 14 CNT (53 ± 6 years) performed 3 sets of 10 unilateral isokinetic knee extension repetitions at 60 °.s−1 on 2 separate days with 2 different RI between sets (1 and 2 min). There was a significant interaction between groups vs. exercise sets (p = 0.03) and RI vs. exercise sets (p < 0.001) for PT. PT was greater in CNT at 1st and 2nd sets compared to BCS group (CNT, 133.4 ± 20.8 and BCS 107.6 ± 19.9 Nm, p = 0.012 and CNT, 118.9 ± 19.6 and BCS, 97.1 ± 15.9 Nm, p = 0.045, respectively). The TW of the knee extensor was significant greater in CNT than BCS group for all 3 knee extension exercise sets. In conclusion, the present study suggests that Breast Cancer Survivors women may need a longer rest interval (longer than 2 min) to be able to fully recover during a 3 sets of isokinetic knee extension exercise training session. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of a single partial-body cryotherapy bout between training sessions on strength recovery. 12 young men (23.9 ± 5.9 years) were randomly exposed to 2 different conditions separated by 7 days: 1) Partial-body cryotherapy (subjects were exposed to 3 min of partial-body cryotherapy at - 110 °C between 2 high-intensity training sessions); 2) Control (subjects were not exposed to partial-body cryotherapy between 2 high-intensity training sessions). Subjects were exposed to partial-body cryotherapy after the first training session. The 2 knee extension high-intensity training sessions were separated by a 40-min rest interval. Knee extension training consisted of 6 sets of 10 repetitions at 60 °.s-1 for concentric actions and 6 sets of 10 at 180.s-1 for eccentric actions. The decrease in eccentric peak torque and total work was significantly (p < 0.05) less after partial-body cryotherapy (5.6 and 2 %, respectively) when compared to control (16 and 11.6 %, respectively). However, the decrease in concentric peak torque and total work was not different (p > 0.05) between partial-body cryotherapy (9.4 and 6.5 %, respectively) and control (7.5 and 5.2 %, respectively). These results indicate that the use of partial-body cryotherapy between-training sessions can enhance eccentric muscle performance recovery. [ABSTRACT FROM AUTHOR]

It has been demonstrated that body cooling may decrease neuromuscular performance. However, the effect of a single session of whole body cryotherapy ( - 110 °C) on neuromuscular performance has not been well documented. Thus, the aim of this study was to evaluate the effects of a single exposure of WBC on elbow flexor neuromuscular performance. Thirteen physically active, healthy young men (age = 27.9 ± 4.2 years, mass = 79.4 ± 9.7 kg, height = 176.7 ± 5.2 cm) were randomly exposed to 2 different experimental conditions separated by a minimum of 72 h: 1) whole body cryotherapy- 3 min at - 110 °C; 2) control- 3 min at 21 °C. All subjects were tested for maximal isokinetic elbow flexion at 60 °.s-1 30 min before and 10 min after each condition. There were no significant differences in peak torque, average power, total work or muscle activity between conditions. Peak torque was lower at post-test compared to pre-test in both conditions (F = 6.58, p = 0.025). However, there were no differences between pre-test and posttest for any other variables. These results indicate that strength specialists, athletic trainers and physical therapists might utilize whole body cryotherapy before training or rehabilitation without compromising neuromuscular performance of the elbow flexors. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate and compare the neuromuscular, morphological and functional adaptations of older women subjected to 3 different types of strength training. 58, healthy women (67 ± 5 year) were randomized to experimental (EG, n = 41) and control groups (CG, n = 17) during the first 6 weeks when the EG group performed traditional resistance exercise for the lower extremity. Afterwards, EG was divided into three specific strength training groups; a traditional group (TG, n = 14), a power group (PG, n = 13) that performed the concentric phase of contraction at high speed and a rapid strength group (RG, n = 14) that performed a lateral box jump exercise emphasizing the stretch-shortening-cycle (SSC). Subjects trained 2 days per week through the entire 12 weeks. Following 6 weeks of generalized strength training, significant improvements occurred in EG for knee extension one-repetition (1RM) maximum strength (+19 %), knee extensor muscle thickness (MT, +15 %), maximal muscle activation (+44 % average) and onset latency (- 31 % average) for vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) compared to CG (p < 0.05). Following 6 more weeks of specific strength training, the 1RM increased significantly and similarly between groups (average of +21 %), as did muscle thickness of the VL (+25 %), and activation of VL (+44 %) and VM (+26 %). The onset latency of RF (TG = 285 ± 109 ms, PG = 252 ± 76 ms, RG = 203 ± 43 ms), reaction time (TG = 366 ± 99 ms, PG = 274 ± 76 ms, RG = 201 ± 41 ms), 30-s chair stand (TG = 18 ± 3, PG = 18 ± 1, RG = 21 ± 2) and counter movement jump (TG = 8 ± 2 cm, PG = 10 ± 3 cm, RG = 13 ± 2 cm) was significantly improved only in RG (p < 0.05). At the end of training, the rate of force development (RFD) over 150 ms (TG = 2.3 ± 9.8 N•s-1, PG = 3.3 ± 3.2 N•s-1, RG = 3.8 ± 6.8 N•s-1, CG = 2.3 ± 7.0 N•s-1) was significantly greater in RG and PG than in TG and CG (p < 0.05). In conclusion, rapid strength training is more effective for the development of rapid force production of muscle than other specific types of strength training and by consequence, better develops the functional capabilities of older women. [ABSTRACT FROM AUTHOR]

Objective: To compare the effects of different rest intervals (RI) between sets of isokinetic contractions on muscle performance in older adults. Methods: Twenty older participants (66.9±3.9 years; 76.1±13.4kg; 169±5.2cm) underwent three sessions of unilateral isokinetic training for the knee extensor muscles, with different RI (1 minute, 2 minutes and 3 minutes) at an angular velocity of 60°⋅s-1. Each session consisted of three sets of 10 repetitions, during which the peak torque (PT), total work (TW) and fatigue index (FI) were evaluated. Factorial ANOVA for repeated measurements, with Bonferroni post-hoc analysis, was used to identify possible differences between the RI. The statistical significance level was set at p<0.05. Results: No differences in muscle performance during the first sets were observed between the different RI (p>0.05). Although muscle performance was lower during the third sets with all RI, the greatest decreases in PT, TW and FI occurred with the 1 minute RI (p<0.05). Conclusion: The results showed that the RI variable has an important influence on isokinetic muscle performance in older adults, particularly from the third sets onwards, which suggests that RI should be increased as successive sets are performed within the same exercise session. [ABSTRACT FROM AUTHOR]