Effects of movement velocity and training frequency of resistance exercise on functional performance in older adults: a randomised controlled trial

Objectives: To investigate the effects that high-velocity, low-load (HVLL) and low-velocity, high-load (LVHL) resistance exercise, performed once or twice-weekly, have on indices of functional performance (primary outcome), maximal strength, and body composition (secondary outcomes) in older adults.

Methods: In a randomised, controlled, multi-armed, parallel design, 54 moderately-highly active, but resistance exercise naïve older adults (aged 60–79 years), attended baseline and post-10-week intervention assessment sessions. Physical and functional assessments were completed, and predicted one-repetition maximums (1-RM) were obtained for eight exercises. Participants were then randomised into one of five conditions: HVLL once-weekly (HVLL1: n?=?11) or twice-weekly (HVLL2: n?=?11), LVHL once-weekly (LVHL1: n?=?10) or twice-weekly (LVHL2: n?=?11), no-exercise control condition (CON: n?=?11). The HVLL conditions completed 3 sets of 14 repetitions at 40% 1-RM and the LVHL conditions, 3 sets of 7 repetitions at 80% 1-RM. In total, 50 participants completed all testing and were included in analyses.

Results: Only LVHL2 improved 30-sec chair stand performance (p?=?.035; g?=?0.89), arm curls (p?=?.011; g?=?1.65) and grip-strength (p?=?.015; g?=?0.34) compared to CON. LVHL2 improved maximal strength compared to CON for 7/8 exercises (p?p?Conclusion: Possibly due to the lower intensity nature of the HVLL conditions, LVHL, twice-weekly was most beneficial for improving functional performance and strength in moderately-highly active older adults. Therefore, we recommend that exercise professionals ensure resistance exercise sessions have sufficient intensity of effort and volume, in order to maximise functional performance and strength gains in older adults.     

Effects of agonist–antagonist complex resistance training on upper body strength and power development

Abstract

The objective of this study was to examine the chronic effects on strength and power of performing complex versus traditional set training over eight weeks. Fifteen trained males were assessed for throw height, peak velocity, and peak power in the bench press throw and one-repetition maximum (1-RM) in the bench press and bench pull exercises, before and after the eight-week programme. The traditional set group performed the pulling before the pushing exercise sets, whereas the complex set group alternated pulling and pushing sets. The complex set training sessions were completed in approximately half the time. Electromyographic (EMG) activity was monitored during both test sessions in an attempt to determine if it was affected as a result of the training programme. Although there were no differences in the dependent variables between the two conditions, bench pull and bench press 1-RM increased significantly under the complex set condition and peak power increased significantly under the traditional set condition. Effect size statistics suggested that the complex set was more time-efficient than the traditional set condition with respect to development of 1-RM bench pull and bench press, peak velocity and peak power. The EMG activity was not affected. Complex set training would appear to be an effective method of exercise with respect to efficiency and strength development.     

Comparison of the musculoskeletal effects of different iso-inertial resistance training modalities: Flywheel vs. electric-motor

Abstract

This study aimed to analyse whether increasing the eccentric overload (EO) during resistance training, in terms of range of motion and/or velocity using an electric-motor device, would induce different muscle adaptations than conventional flywheel-EO resistance training. Forty physically active university students (21.7?±?3.4 years) were randomly placed into one of the three training groups (EX1, EX2, FW) and a control group without training (n?=?10 per group). Participants in the training groups completed 12 sessions (4 sets of 7 repetitions) of iso-inertial single-leg squat training over 6 weeks for the dominant leg. Resistance was generated either by an electric-motor device at two different velocities for the eccentric phase; 100% (EX1) or 150% (EX2) of concentric speed, or by a conventional flywheel device (FW). Thigh lean tissue mass, unilateral leg press one-repetition maximum (1-RM), unilateral muscle power at different percentages of the 1-RM and bilateral/unilateral vertical jump were assessed before and after the 6-week training. There were significant (p?<?0.05–0.001) main effects of time in the 3 training groups, indicating increased thigh lean tissue mass (2.5–5.8%), 1-RM load (22.4–30.2%), vertical jump performance (9.1–32.9%) and muscle power (8.8–21.7%), without differences across experimental groups. Participants in the control group did not improve any of the variables measured. In addition, EX2 showed greater gains in eccentric average peak power during training than EX1 and FW (p?<?0.001). Despite the different EO offered, 6 weeks of resistance training using flywheel or electric-motor devices induced similar significant gains in muscle mass, strength, muscle power and vertical jump.     

Radial and tibial bone indices in athletes participating in different endurance sports: a pQCT study†

Low magnitude bone-loading sports may benefit bone structure and strength in the exercised limbs. This study compared peripheral quantitative computed tomography measures of radial and tibial diaphyseal strength (strength–strain index, SSI), structure (total area (ToA) and cortical area (CoA), density (CoD) and thickness (CT), and circumferences), muscle cross-sectional area (MCSA) and strength (one-repetition maximum, 1-RM) in male endurance athletes taking part in (i) non-weight-bearing and non-impact sports: swimmers (SWIM, n?=?13) and road cyclists (RC, n?=?10), (ii) non-weight-bearing, impact sport: mountain bikers (MB, n?=?10), (iii) weight bearing and impact sport: runners (RUN, n?=?9). All athlete groups were also compared to sedentary controls (CON, n?=?10). Arm MCSA, 1-RM and radial bone size and strength tended to be greater in SWIM than CON and/or RC (ToA, %difference ±?95%CI, SWIM-CON: 14.6%?±?12.7%; SWIM-RC: 12.9%?±?10.7%) but not different to MB and RUN. RUN had bigger tibial CoA than CON, SWIM and RC (CoA, RUN-CON: 12.1%?±?10.7%; RUN-SWIM: 10.9%?±?9.4%; RUN-RC: 15.8%?±?9.5%) without marked changes in tibial strength indices, lower-limb MCSA or 1-RM. Both MB and RC failed to display any difference in tibial indices, lower-limb MCSA and 1-RM compared to CON. In swimmers, the bone structure and strength of the primary exercised limbs, the arms, is greater than controls and road cyclists. Conversely, although runners experience impact and weight-bearing loading, tibial structure is greater without a substantial difference in tibial strength compared to controls and non-impact sports. Failure to observe a difference in tibial indices in MB and RC compared to controls is unexpected.     

Physiological and Anatomical Characteristics Of Outstanding Female Junior Tennis Players

Purpose: The purpose of this study was to investigate the physiological adaptations of resistance training (RT) in prepubertal boys. Methods: Eighteen healthy boys were divided into RT (n = 9, M_age = 10.4 ± 0.5 years) and control (CTR; n = 9, M_age = 10.9 ± 0.7 years) groups. The RT group underwent a resistance training during 12 weeks, 3 times per week, performing 3 sets of 6 to 15 repetitions at intensities ranging from 60% to 80% of maximal dynamic strength (1-repetition maximum [1-RM] values). Before and after the training, the groups were assessed in their body mass and composition (dual-energy X-ray absorptiometry), isokinetic dynamometry, 1-RM, and ergoespirometry. Moreover, force per unit of muscle volume was calculated by the quotient between 1-RM and lean mass. Results: Both groups presented statistically significant (p < .05) increases in the 1-RM and force per unit of muscle volume in the knee extension and elbow flexion, but these strength increases were statistically significantly greater in the RT group (effect size [ES] = 2.83–9.00) than in the CTR group (ES = 0.72–1.00). Moreover, both groups statistically significantly increased in lean body mass variables (ES = 0.12–0.38). However, increases in the fat mass variables occurred only in the CTR group (ES = ? 0.01–0.50), whereas no changes were observed in the RT group. Furthermore, there were statistically significant increases in all bone mineral content variables (ES = 0.13–0.43), without differences between groups. No cardiorespiratory changes were observed. Conclusion: Twelve weeks of RT was effective in improving strength and force per unit of muscle volume and prevented fat mass increases in boys.     

Relationships among peak power output,peak bar velocity,and mechanomyographic amplitude during the free-weight bench press exercise

Abstract

The purpose of this study was to examine the relationships among mechanomyographic (MMG) amplitude, power output, and bar velocity during the free-weight bench press exercise. Twenty-one resistance-trained men [one-repetition maximum (1-RM) bench press = 125.4 ± 18.4 kg] performed bench press muscle actions as explosively as possible from 10% to 90% of the 1-RM while peak power output and peak bar velocity were assessed with a TENDO Weightlifting Analyzer. During each muscle action, surface MMG signals were detected from the right and left pectoralis major and triceps brachii, and the concentric portion of the range of motion was selected for analysis. Results indicated that power output increased from 10% to 50% 1-RM, followed by decreases from 50% to 90% 1-RM, but MMG amplitude for each of the muscles increased from 10 to 80%1-RM. The results of this study indicate that during the free-weight bench press exercise, MMG amplitude was not related to power output, but was inversely related to bar velocity and directly related to the external load being lifted. In future research, coaches and sport scientists may be able to estimate force/torque production from individual muscles during multi-joint, dynamic constant external resistance muscle actions.     

Bilateral deficit in power production during multi-joint leg extensions

Abstract

The purpose of this study was to determine the presence of the bilateral deficit both as a function of overall and individual joint power. Most studies addressing the deficit have assessed force; however, in most sporting events maximal power is more important than maximal force production. To address this, in the current study we assessed the bilateral deficit for multi-joint movements as measured by overall lower extremity and individual joint power. We assessed power production using an isokinetic machine permitting both unilateral and bilateral leg extensions. Several significant effects and interactions between the contraction type (unilateral, bilateral, alternating unilateral), side of the body, lower extremity joint, and percentage of a 1-RM load were revealed. All interactions were between the lower extremity joints (hip, knee, ankle) and involved the contraction protocol (P=0.001), the percentage of 1-RM load (P=0.0002), and the side of the body (P=0.0003). Taken together, the results indicate that the bilateral deficit is manifested using a measure of power, but more importantly, the deficit has differential implications based on the overall resistance, and various joints involved in the movement. In conclusion, a reduction in power generation was evidenced for both simultaneous contractions of the leg extensors as well as reciprocal contractions. With reduced contributions from the knee joint during bilateral and reciprocal contractions, combined with past research demonstrating differential activation of mono-articular knee joint muscles, evidence for reduced contributions from the peripheral nervous system are suggested based on the results of this study.     

The influence of isometric preload on power expressed during bench press in strength-trained men

The purpose of this study was to compare the power expressed during the bench press exercise in resistance-trained men following different pre-activation conditions. Twenty-two trained men (age 24.1?±?1.7 years, height 178.6?±?6.1?cm, body mass 81.1?±?10.6?kg) completed a maximal effort bench press (1-RM) test (100.0?kg?±?8.1?kg). In a subsequent assessment, each participant performed concentric bench press movements with loads of 20%, 30%, 40% and 50% of their 1-RM preceded by either a concentric contraction (CC), a low isometric preload (LIP; 70% 1-RM) or a high isometric preload (HIP; 100% 1-RM) conditions. All movements were performed in a Smith machine with a settable quick-release device. Participants performed all three conditions in randomized fashion. Results indicated that power outputs during the bench press exercise following HIP were significantly (p?<?0.05) greater than CC at 20% 1-RM (+9%), 30% 1-RM (+16%) and 40% 1-RM (+14%), and LIP at 20% 1-RM (+4%), 30% 1-RM (+20%) and 40% 1-RM (+15%). No differences were found between conditions at 50% 1-RM. Area under the force–power curve with HIP was greater (p?<?0.05) than with CC and LIP. In conclusion, results of this study indicate that the use of a HIP (100% 1-RM) in trained participants results in significantly greater power output during the concentric phase of a multi-joint exercise when compared to standard concentric movement.     

Effects of rest interval during high-repetition resistance training on strength,aerobic fitness,and repeated-sprint ability

Abstract

The effect of altering the rest period on adaptations to high-repetition resistance training is not well known. Eighteen active females were matched according to leg strength and repeated-sprint ability and randomly allocated to one of two groups. One group performed resistance training with 20-s rest intervals between sets, while the other group employed 80-s rest intervals between sets. Both groups performed the same total training volume and load. Each group trained 3 days a week for 5 weeks [15- to 20-repetition maximum (RM), 2 – 5 sets]. Repeated-sprint ability (5×6-s maximal cycle sprints), 3-RM leg press strength, and anthropometry were determined before and after each training programme. There was a greater improvement in repeated-sprint ability after training with 20-s rest intervals (12.5%) than after training with 80-s rest intervals (5.4%) (P = 0.030). In contrast, there were greater improvements in strength after training with 80-s rest intervals (45.9%) than after training with 20-s rest intervals (19.6%) (P = 0.010). There were no changes in anthropometry for either group following training. These results suggest that when training volume and load are matched, despite a smaller increase in strength, 5 weeks of training with short rest periods results in greater improvements in repeated-sprint ability than the same training with long rest periods.     

Electromyographic Study of Selected Muscles Involved in Movements of Upper Arm at Scapulohumeral Joint

Abstract

This article presents an investigation, by means of electromyography, of the functions of the biceps brachii, the deltoideus, the latissimus dorsi, the pectoralis major, the serratus anterior, the cleido mastoideus, the teres major, the trapezius, and the triceps brachii (long head) in movements of the upper arm and the shoulder girdle at scapulo-humeral, acromioclavicular, and sternoclavicular joints. The procedure for collecting the data was established on the basis of records taken on twelve subjects; and the findings that are reported were based on 20 complete sets taken on five subjects.     

Intensity of Treadmill Training and its Effect on Body Composition in Rats

Abstract

The purpose of this study was to determine which of three intensities of treadmill training produced changes in body composition in rats as evidenced by body weight, percentage of fat and specific gravity. Subjects were 60 male Wistar rats 25 to 30 days old when obtained. They were randomly assigned to one of five groups: sedentary controls, spontaneously active controls, and three groups of rats forced to exercise on a treadmill at intensities of 75, 125 and 175 fpm. Forced exercise was applied three times a week for 8 weeks, after which measures of body weight, specific gravity, and percentage of body fat were obtained. Results indicated that the sedentary controls had significantly higher mean body weights than did those which exercised. Rats forced to exercise at 75 fpm had significantly lower specific gravity measures than rats trained at 125 fpm. Sedentary controls had lower specific gravity values than did all rats allowed to exercise. Intensity of treadmill training had no effect on percentage of body fat as determined chemically. However, exercise was effective in reduction of body fat.     

Effect of individualized resistance training prescription with heart rate variability on individual muscle hypertrophy and strength responses

Abstract

The aim of the present study was to investigate if resistance training (RT), performed with individualized recovery between sessions (RT-IND), promotes greater gains in strength and muscle mass and reduces the variability on adaptations compared to RT with fixed recovery intervals (RT-FIX). Twenty young men (age 21.9?±?3.3 years) were randomized in the RT-IND and RT-FIX groups. Five days before the beginning of the training, measurements of the root mean square of successive R-R intervals differences (RMSSD) values of each individual were performed to establish the baseline values. Before each RT session, the RMSSD values determined whether the participants from RT-IND protocol were recovered from the previous session. Participants performed the RT session only if RMSSD values had returned to the baseline, otherwise they had to wait for an additional 24?h. RT-FIX performed an RT session every 48?h. Muscle strength was measured by one-maximal repetition (1-RM) test and muscle cross-section area (CSA) of the vastus laterals by ultrasonography were assessed pre- and post-training. 1-RM values increased significantly from pre to post-training for both groups (RT-IND: 30% and RT-FIX: 42%, main time effect, P?<?0001), with no significant difference between groups. Muscle CSA increased significantly from pre to post-training (RT-IND: 15.7% and RT-FIX: 15.8%, main time effect, P?<?0001), with no significant difference between groups. In conclusion, RT-IND did not increase the gains in muscle strength and mass neither reduce the variability in muscle adaptations when compared to the RT-FIX.     

Improving cognitive and physical function through 12-weeks of resistance training in older adults: Randomized controlled trial

ABSTRACT

We performed a randomized, controlled trial to analyse the effects of resistance training (RT) on cognitive and physical function among older adults. Fifty participants (mean age 67 years, ~60% woman) were randomly assigned to an RT program or a control group. Participants allocated to RT performed three sets of 10-15RM in nine exercises, three times per week, for 12-weeks. Control group did not perform any exercise. Variables included cognitive (global and executive function) and physical function (gait, mobility and strength) outcomes. At completion of the intervention, RT was shown to have significantly mitigated the drop in selective attention and conflict resolution performance (Stroop test: -494.6; 95%CI: -883.1; ?106.1) and promoted a significant improvement in working memory (digit span forward: -0.6; 95%CI: ?1.0; ?0.1 and forward minus backward: -0.9; 95% CI: ?1.6; ?0.2) and verbal fluency (animal naming: +1.4, 95%CI 0.3, 2.5). No significant between-group differences were observed for other cognitive outcomes. Regarding physical function, at completion of the intervention, the RT group demonstrated improved fast-pace gait performance (?0.3; 95% CI: ?0.6; ?0.0) and 1-RM (+21.4 kg; 95%CI: 16.6; 26.2). No significant between-group differences were observed for other mobility-related outcomes. In conclusion, RT improves cognitive and physical function of older adults.     

The Influence of Strength on Speed of Movement in Eighth Grade Girls

Abstract

The purpose of this study was twofold: to determine which exercise program was most effective in producing a static strength gain and to determine the relationship between static strength and speed of movement. Seventy-two eighth grade girls were divided into two experimental groups one using an isometric exercise program, the other using an isotonic program. A control group played lead-up games during the experimental period. Strength and speed of the arm and shoulder girdle were both measured by three tests. Prior to training, correlations indicated a rather high relationship between static strength, and speed of a dominant arm movement. Following training there was little relationship between static strength, and speed of a specific arm movement. The results of the training program indicated an increase in mean performance in all three groups with the isotonic group being superior.     

Chain-loaded variable resistance warm-up improves free-weight maximal back squat performance

The acute influence of chain-loaded variable resistance exercise on subsequent free-weight one-repetition maximum (1-RM) back squat performance was examined in 16 recreationally active men. The participants performed either a free-weight resistance (FWR) or chain-loaded resistance (CLR) back squat warm-up at 85% 1-RM on two separate occasions. After a 5-min rest, the participants attempted a free-weight 1-RM back squat; if successful, subsequent 5% load additions were made until participants failed to complete the lift. During the 1-RM trials, 3D knee joint kinematics and knee extensor and flexor electromyograms (EMG) were recorded simultaneously. Significantly greater 1-RM (6.2?±?5.0%; p?p?p?>?.05) was found in concentric EMG, eccentric or concentric knee angular velocity, or peak knee flexion angle. Performing a CLR warm-up enhanced subsequent free-weight 1-RM performance without changes in knee flexion angle or eccentric and concentric knee angular velocities; thus a real 1-RM increase was achieved as the mechanics of the lift were not altered. These results are indicative of a potentiating effect of CLR in a warm-up, which may benefit athletes in tasks where high-level strength is required.     

Effects of circuit low-intensity resistance exercise with slow movement on oxygen consumption during and after exercise

The purpose of this study was to examine oxygen consumption (VO(2)) during and after a single bout of low-intensity resistance exercise with slow movement. Eleven healthy men performed the following three types of circuit resistance exercise on separate days: (1) low-intensity resistance exercise with slow movement: 50% of one-repetition maximum (1-RM) and 4 s each of lifting and lowering phases; (2) high-intensity resistance exercise with normal movement: 80% of 1-RM and 1 s each of lifting and lowering phases; and (3) low-intensity resistance exercise with normal movement: 50% of 1-RM and 1 s each of lifting and lowering phases. These three resistance exercise trials were performed for three sets in a circuit pattern with four exercises, and the participants performed each set until exhaustion. Oxygen consumption was monitored continuously during exercise and for 180 min after exercise. Average VO(2) throughout the exercise session was significantly higher with high- and low-intensity resistance exercise with normal movement than with low-intensity resistance exercise with slow movement (P < 0.05); however, total VO(2) was significantly greater in low-intensity resistance exercise with slow movement than in the other trials. In contrast, there were no significant differences in the total excess post-exercise oxygen consumption among the three exercise trials. The results of this study suggest that low-intensity resistance exercise with slow movement induces much greater energy expenditure than resistance exercise with normal movement of high or low intensity, and is followed by the same total excess post-exercise oxygen consumption for 180 min after exercise.     

Examining the intrinsic foot muscles’ capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping

BackgroundDuring human locomotion, a sufficiently stiff foot allows the ankle plantar flexors to generate large propulsive powers. Increasing foot stiffness (e.g., via a carbon plate) increases the ankle's external moment arm in relation to the internal moment arm (i.e., increasing gear ratio), reduces plantar flexor muscles’ shortening velocity, and enhances muscle force production. In contrast, when activation of the foot's intrinsic muscles is impaired, there is a reduction in foot and ankle work and metatarsophalangeal joint stiffness. We speculated that the reduced capacity to actively control metatarsophalangeal joint stiffness may impair the gearing function of the foot at the ankle.MethodsWe used a tibial nerve block to examine the direct effects of the intrinsic foot muscles on ankle joint kinetics, in vivo medial gastrocnemius’ musculotendinous dynamics, and ankle gear ratio on 14 participants during maximal vertical jumping.ResultsUnder the nerve block, the internal ankle plantar flexion moment decreased (p = 0.004) alongside a reduction in external moment arm length (p = 0.021) and ankle joint gear ratio (p = 0.049) when compared to the non-blocked condition. Although medial gastrocnemius muscle–tendon unit and fascicle velocity were not different between conditions, the Achilles tendon was shorter during propulsion in the nerve block condition (p < 0.001).ConclusionIn addition to their known role of regulating the energetic function of the foot, our data indicate that the intrinsic foot muscles also act to optimize ankle joint torque production and leverage during the propulsion phase of vertical jumping.     

Instructions to Adopt an External Focus Enhance Muscular Endurance

Abstract

The influence of internal (movement focus) and external (outcome focus) attentional-focusing instructions on muscular endurance were investigated using three exercise protocols with experienced exercisers. Twenty-three participants completed a maximal repetition, assisted bench-press test on a Smith's machine. An external focus of attention resulted in significant (p < .05) improvements in performance compared to the internal focus of attention, but not the control condition. Seventeen participants completed repetitions to failure at 75% 1-RM on free bench-press and squat exercises. In both tasks, externally focused instructions resulted in significantly greater repetitions to failure than control and internal focus conditions (p < .05). These results support previous research showing beneficial effects of externally focused instructions on movement efficiency.     

Fatigue effects upon sticking region and electromyography in a six-repetition maximum bench press

Abstract

The aim of the study was to examine the sticking region and concomitant neuromuscular activation of the prime movers during six-repetition maximum (RM) bench pressing. We hypothesised that both peak velocities would decrease and that the electromyography (EMG) of the prime movers (deltoid, major pectoralis and triceps) would increase during the pre-sticking and sticking region during the six repetitions due to fatigue. Thirteen resistance-trained males (age 22.8 ± 2.2 years, stature 1.82 ± 0.06 m, body mass 83.4 ± 7.6 kg) performed 6-RM bench presses. Barbell kinematics and EMG activity of pectoralis major, deltoid anterior, and triceps brachii during the pre-, sticking and post-sticking region of each repetition in a 6-RM bench press were analysed. For both the sticking as the post-sticking region, the time increased significantly from the first to the sixth repetition. Vertical barbell height at the start of sticking region was lower, while the height at the end of the sticking region and post-sticking region did not change during the six repetitions. It was concluded that in 6-RM bench pressing performance, the sticking region is a poor mechanical force region due to the unchanged barbell height at the end of the sticking region. Furthermore, when fatigue occurs, the pectoralis and the deltoid muscles are responsible for surpassing the sticking region as indicated by their increased activity during the pre- and sticking region during the six-repetitions bench press.     

Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players

Abstract

We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.