Explosive-type Strength Training Research Articles

Increased Fatigability in Women With Persistent Cancer-Related Fatigue After Breast Cancer Treatment: A Pilot Study

Purpose: To examine whether survivors of breast cancer (SBC) with persistent cancer-related fatigue (CRF) have greater fatigability than their nonfatigued counterparts. Methods: Measures of fatigability, including endurance, perceived exertion, lower extremity muscle force and power, and sit-to-stand time (STST), were assessed in 43 women (21 with persistent CRF) after a sit-to-stand fatigue (STSF) task. Group differences in fatigability outcomes were examined using analysis of variance. Results: SBC with persistent CRF had lower endurance (P = .003, ηp 2 = 0.205) and reported greater perceived exertion (P < .001, ηp 2 = 0.284) during the STSF task, and demonstrated lower postexertional force (P = .035, ηp 2 = 0.109), power (P = .001, ηp 2 = 0.242), and slower STST (P = .001, ηp 2 = 0.258) compared with SBC without CRF. Conclusions: SBC with persistent CRF have increased fatigability compared with those without CRF. Our findings suggest that exercise recommendations for women with persistent CRF after breast cancer treatment should include activities that increase lower limb muscle force and power, such as heavy resistance or explosive-type strength training.

Effects of 4 Weeks of Explosive-type Strength Training for the Plantar Flexors on the Rate of Torque Development and Postural Stability in Elderly Individuals.

This study aimed to investigate the effect of a 4-week explosive-type strength training program for the plantar flexors on the rate of torque development and postural stability. The participants were 56 elderly men and women divided into training (17 men and 15 women) and control (14 men and 10 women) groups. The participants in the training group underwent explosive-type strength training of the plantar flexors 2 days per week for 4 weeks. Training consisted of 3 sets of 10 repetitions of explosive plantar flexion lasting less than 1 s. The following parameters were determined: muscle volume of the plantar flexors estimated by the muscle thickness and lower leg length, maximal voluntary contraction torque and rate of torque development of plantar flexion, and one-leg standing ability. The training increased the maximal voluntary contraction torque and rate of torque development, but corresponding increases in muscle volume and one-leg standing ability were not found. These results suggest that, for elderly individuals, the 4-week explosive-type strength training of the plantar flexors is effective for increasing the maximal voluntary contraction torque and rate of torque development of plantar flexion but is not effective for improving postural stability.

Effects of Explosive Type Strength Training on Selected Physical and Technical Performance Characteristics in Middle Distance Running - a Case Report

Abstract Introduction . Distance running performance is a simple function of developing high speeds and maintaining this speed as long as possible. Thus a correct running technique becomes an important component of performance. Technique is effective if the competitor can reach a better performance result with the same or lower energy consumption. The purpose of this investigation was to examine a six weeks application explosive type strength training on lower extremities power and maximum speed performance improvement in order to facilitate running technique in sub-elite male middle-distance runner. Material and methods . A sub-elite runner performed twice a week special exercises and running drills. He completed a pre and post-training jumping (SJ, CMJ, standing long jump, standing five jump) and speed (20 m from standing and flying start) field tests. For kinematical analysis, a video (SIMI Motion System) of a 10 m sprint from a 20 m flying start was collected. Results . Improvement occurred in all measurements but strong changes were evident in the 10 m from 20 flying start and in stride frequency from 3.90 to 4.01 Hz, due to decreasing of ground contact time from 160 to 156 ms. No strong evidence in the participant's running technique changes. Conclusion . This proved that six weeks of dynamic type strength program seems to improve neuromuscular characteristics of running speed and explosive power and no changes in running technique.

EFFECT OF EXPLOSIVE-TYPE STRENGTH TRAINING AND SHORT-TERM DETRAINING ON RATE OF TORQUE DEVELOPMENT DURING ISOMETRIC KNEE EXTENSION

Rate of torque development (RTD) is considered important for improving the performance in sports requiring explosive strength. Although RTD was reported to be increased after explosive-type strength training (Tillin et...

Stair-Ascent Performance in Elderly Women: Effect of Explosive Strength Training

Explosive-type strength training may alter kinetics and neuromuscular activity during stair ascent in elderly women. This may improve functional ability. Nineteen women (69.7 ± 3.4 yr) were randomly allocated to strength training (TG; twice per wk, 12 wk) or a control group (CG). Stair ascent was assessed at self-chosen (AFV), standardized (ASV), and maximal velocity (AMV) pre- and posttraining. Ground-reaction force (GRF) and EMG quantified kinetics and neuromuscular activity. After training, TG increased AMV and AFV velocity by 8% (p = .02) and 17% (p= .007), respectively (TG vs. CG; p< .05). This was accompanied by elevated rectus femoris EMG (from 21% to 48%, p< .047). At AFV, TG increased GRF first peak force 4% (p= .047), and CG increased second peak force 5% (p = .036). Muscle coactivation remained unaltered in both groups. Explosive-type strength training led to enhanced stair-climbing performance at maximal and self-chosen speed, reflecting an improved functional ability.

Concurrent Endurance and Explosive Type Strength Training Improves Neuromuscular and Anaerobic Characteristics in Young Distance Runners

To study effects of concurrent explosive strength and endurance training on aerobic and anaerobic performance and neuromuscular characteristics, 13 experimental (E) and 12 control (C) young (16 - 18 years) distance runners trained for eight weeks with the same total training volume but 19% of the endurance training in E was replaced by explosive training. Maximal speed of maximal anaerobic running test and 30-m speed improved in E by 3.0 +/- 2.0% (p < 0.01) and by 1.1 +/- 1.3% (p < 0.05), respectively. Maximal speed of aerobic running test, maximal oxygen uptake and running economy remained unchanged in both groups. Concentric and isometric leg extension forces increased in E but not in C. E also improved (p < 0.05) force-time characteristics accompanied by increased (p < 0.05) rapid neural activation of the muscles. The thickness of quadriceps femoris increased in E by 3.9 +/- 4.7% (p < 0.01) and in C by 1.9 +/- 2.0% (p < 0.05). The concurrent explosive strength and endurance training improved anaerobic and selective neuromuscular performance characteristics in young distance runners without decreases in aerobic capacity, although almost 20% of the total training volume was replaced by explosive strength training for eight weeks. The neuromuscular improvements could be explained primarily by neural adaptations.

Concurrent Endurance and Explosive Type Strength Training Increases Activation and Fast Force Production of Leg Extensor Muscles in Endurance Athletes

The purpose of this experiment was to examine the effects of concurrent endurance and explosive strength training on electromyography (EMG) and force production of leg extensors, sport-specific rapid force production, aerobic capacity, and work economy in cross-country skiers. Nineteen male cross-country skiers were assigned to an experimental group (E, n = 8) or a control group (C, n = 11). The E group trained for 8 weeks with the same total training volume as C, but 27% of endurance training in E was replaced by explosive strength training. The skiers were measured at pre- and post training for concentric and isometric force-time parameters of leg extensors and EMG activity from the vastus lateralis (VL) and medialis (VM) muscles. Sport-specific rapid force production was measured by performing a 30-m double poling test with the maximal velocity (V(30DP)) and sport-specific endurance economy by constant velocity 2-km double poling test (CVDP) and performance (V(2K)) by 2-km maximal double poling test with roller skis on an indoor track. Maximal oxygen uptake (Vo(2)max) was determined during the maximal treadmill walking test with the poles. The early absolute forces (0-100 ms) in the force-time curve in isometric action increased in E by 18 +/- 22% (p < 0.05), with concomitant increases in the average integrated EMG (IEMG) (0-100 ms) of VL by 21 +/- 21% (p < 0.05). These individual changes in the average IEMG of VL correlated with the changes in early force (r = 0.86, p < 0.01) in E. V(30DP) increased in E (1.4 +/- 1.6%) (p < 0.05) but not in C. The V(2K) increased in C by 2.9 +/- 2.8% (p < 0.01) but not significantly in E (5.5 +/- 5.8%, p < 0.1). However, the steady-state oxygen consumption in CVDP decreased in E by 7 +/- 6% (p < 0.05). No significant changes occurred in Vo(2)max either in E or in C. The present concurrent explosive strength and endurance training in endurance athletes produced improvements in explosive force associated with increased rapid activation of trained leg muscles. The training also led to more economical sport-specific performance. The improvements in neuromuscular characteristics and economy were obtained without a decrease in maximal aerobic capacity, although endurance training was reduced by about 20%.

Explosive-type Strength Training in the Elderly

The age-related decline in muscle power and explosive force capacity (i.e. contractile rate of force development RFD) is as stronger predictor for incidence of falling, motor impairment, self-reported functional status and balance capability in community-dwelling old adults than maximal muscle strength per se. It was therefore recently suggested to develop strength training programmes aimed at maximising maximal muscle power and RFD by implementing explosive concentric movements with training loads of 40–60% of 1RM. However, older individuals often perform weight-bearing motor tasks close to their maximum capability (i.e. 1RM) and above especially during unexpected tasks such as reversing an impending fall. PURPOSE: To investigate the effect of 12-week, twice a week, heavy-resistance strength training (75–80 % of 1RM) with fast-to-explosive execution of the movements on maximal voluntary contraction (MVC), explosive force characteristics (RFD and impulse), muscle power and functional performances in two age-groups of community-dwelling elderly women (TG60, TG80, age-groups 60 and 80, respectively). METHODS: Elderly women from two age-groups, 60 (62.7 2.2 years, n=40) and 80 (81.8 2.7 years, n=25) were randomized (matched) into two training and two control groups (TG60, n=20; TG80, n=12) (CG 60, n=20; CG80, n=13). MVC, RFD and impulse were obtained during a maximal isometric unilateral leg press manuevre. Mechanical performance was assessed as jump height, (JH) and peak power (Ppeak) in a standardized countermovement jump (CMJ) and as mean power (Prigmean). in the Nottingham single-legged power rig. Functional motor performances were i) five-repeated chair rise, ii) 10-m walking test at self selected and maximal speed, and iii) Physical Performance Test (PPT). RESULTS: RFD, impulse, MVC, P peak', JH and Prigmean increased with training in both age-groups. The gains in RFD (50.5%), impulse (41.9%) and MVC (28.1%) for TG 80 were of such a magnitude that the difference observed pre intervention with the age-group 60 was abolished after training. Chair-rise and PPT improved in TG80 and only chair rise in TG60, whereas no improvements occurred in self-selected and maximal 10-meter gait speed. CONCLUSIONS: The present findings indicate that heavy-resistance strength training performed with explosive movement characteristics is highly effective in inducing adaptive neuromuscular changes in selected physiological variables and functional performances commonly associated with risk of falls and disability in aged individuals. This training modality seems to be safe and suitable for healthy women even in the 8th decade of life.

Effects of Concurrent Endurance and Explosive Type Strength Training on Neuromuscular Characteristics in Endurance Athletes

Introduction: In previously untrained male and women subjects explosive type strength training results in great increases in the amount of neural input to the trained muscles contributing largely to the improvements in explosive force production (Häkkinen 1994). It has been suggested, that also in endurance athletes, during relatively short training periods of some weeks, the improvements in force and velocity characteristics might primarily come from neural adaptations, although no electromyographic (EMG) measurements on the muscles have been performed to support this suggestion (Paavolainen et al. 1999). Therefore, the aim of the present study was to investigate the effects of concurrent endurance and explosive strength training on EMG and force production characteristics of leg extensor muscles in well-trained endurance athletes. Methods: Six experimental (E) and 6 control (C) endurance athletes trained for 8 wk. The total training volume was kept the same in both groups, but 26% of training in E and 2% in C was replaced by explosive type strength training. It consisted of various concentric and stretch-shortening cycle exercises for leg extensor muscles performed with low loads but high velocities. A dynamometer was used to measure maximal bilateral isometric force and various force-time parameters of the leg extensor muscles. Three to five maximal isometric actions were performed at the knee and hip angles of 90°. EMG-activity was recorded from the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles of the right leg. Results: Maximal isometric force did not change after 8-wk training but in E the average force-time curve changed in the absolute scale so that the times to reach lower force levels shortened (p < 0.01) and early forces (in 0–100 ms) increased (p < 0.01). Maximal average integrated EMG (AEMG) of the VL, VM and RF muscles increased in E during training and the changes were significant (p < 0.05–0.01) in the early portions of the isometric actions. No changes were observed in C. In E the relative increases in the AEMG of VL (0–100 ms) correlated with the relative increases in force (0–100 ms) (r = 0.82, p < 0.05). Discussion: The present 8-wk explosive type strength training resulted in considerable improvements in selected neuromuscular characteristics, although a large volume of endurance training was performed concomitantly. This supports previous findings (e.g. Paavolainen et al. 1999) that in well-trained endurance athletes training-induced improvements in neuromuscular characteristics may not be fully inhibited by concurrent explosive strength and endurance training. A specific training-induced shift in the “early” portions of the AEMG-time curve indicated that the improvements in explosive force production were largely due to neural adaptations. The importance of the neural component was further supported by the correlation between the changes in the early AEMG and the changes in explosive force production during the early part of the isometric force-time curve. No changes were observed in maximal isometric force during training which further supports the concept of specificity of training, since the training program did not include resistance exercises with high loads.

The effects of replacing a portion of endurance training by explosive strength training on performance in trained cyclists.

To investigate the effects of replacing a portion of endurance training by strength training on exercise performance, 14 competitive cyclists were divided into an experimental (E; n = 6) and a control (C; n = 8) group. Both groups received a training program of 9 weeks. The total training volume for both groups was the same [E: 8.8 (1.1) h/week; C: 8.9 (1.7) h/week], but 37% of training for E consisted of explosive-type strength training, whilst C received endurance training only. Simulated time trial performance (TT), short-term performance (STP), maximal workload (Wmax) and gross (GE) and delta efficiency (DE) were measured before, after 4 weeks and at the end of the training program (9 weeks). No significant group-by-training effects for the markers of endurance performance (TT and Wmax) were found after 9 weeks, although after 4 weeks, these markers had only increased (P < 0.05) in E. STP decreased (P < 0.05) in C, whereas no changes were observed in E. For DE, a significant group-by-training interaction (P < 0.05) was found, and for GE the group-by-training interaction was not significant. It is concluded that replacing a portion of endurance training by explosive strength training prevents a decrease in STP without compromising gains in endurance performance of trained cyclists.

Effects of explosive type strength training on physical performance characteristics in cross-country skiers

To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6-9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P less than 0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P less than 0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.

Training-induced changes in neuromuscular performance under voluntary and reflex conditions.

To investigate training-induced changes in neuromuscular performance under voluntary and reflex contractions, 11 male subjects went through heavy resistance (high loads of 70-120% of one maximum repetition) and 10 male subjects through explosive type (low loads with high contraction velocities) strength training three times a week for 24 weeks. A large increase (13.9%, p less than 0.01) in voluntary unilateral maximal knee extension strength with only slight and insignificant changes in time of isometric force production were observed during heavy resistance strength training. Explosive type strength training resulted in a small insignificant increase in maximal strength but in considerable shortening (p less than 0.05) in the time of force production. A significant increase (p less than 0.05) noted in the averaged maximal integrated electromyogram (IEMG) of the knee extensors during heavy resistance strength training correlated (p less than 0.01) with the increase in maximal strength. No changes were noted during training in reflex time components, but significant decreases (p less than 0.05) occurred in the peak-to-peak amplitudes of the reflex electromyograms (EMG) in both groups. The individual changes during training in the reflex EMG/force ratio were related (p less than 0.01) to the respective changes in IEMG/force ratio in voluntary contractions. The present observations support the concept of specificity of training, and suggest that specific training-induced adaptations in the neuromuscular system may be responsible for these changes in performance.

Changes in isometric force- and relaxation-time, electromyographic and muscle fibre characteristics of human skeletal muscle during strength training and detraining.

Eleven male subjects (20-32 years) accustomed to strength training went through progressive, high-load strength training for 24 weeks with intensities ranging variably between 70 and 120% during each month. This training was also followed by a 12-week detraining period. An increase of 26.8% (P less than 0.001) in maximal isometric strength took place during the training. The increase in strength correlated (P less than 0.05) with significant (P less than 0.05-0.01) increases in the neural activation (IEMG) of the leg extensor muscles during the most intensive training months. During the lower-intensity training, maximum IEMG decreased (P less than 0.05). Enlargements of muscle-fibre areas, especially of fast-twitch type (P less than 0.001), took place during the first 12 weeks of training. No hypertrophic changes were noted during the latter half of training. After initial improvements (P less than 0.05) no changes or even slight worsening were noted in selected force-time parameters during later strength training. During detraining a great (P less than 0.01) decrease in maximal strength was correlated (P less than 0.05) with the decrease (P less than 0.05) in the maximum IEMGs of the leg extensors. This period resulted also in decreases (P less than 0.05) of the mean muscle-fibre areas of both fibre types. It was concluded that improvement in strength may be accounted for by neural factors during the course of very intensive strength training. Selective training-induced hypertrophy also contributed to strength development but muscle hypertrophy may have some limitations during long-lasting strength training, especially in highly trained subjects.

Effect of explosive type strength training on isometric force- and relaxation-time, electromyographic and muscle fibre characteristics of leg extensor muscles.

To investigate the influence of explosive type strength training on isometric force- and relaxation-time and on electromyographic and muscle fibre characteristics of human skeletal muscle, 10 male subjects went through progressive training which included primarily jumping exercises without extra load and with light extra weights three times a week for 24 weeks. Specific training-induced changes in force-time curve were observed and demonstrated by great (P less than 0.05-0.01) improvements in in parameters of fast force production and by a minor (P less than 0.05) increase in maximal force. The continuous increases in fast force production during the entire training were accompanied by and correlated with the increases (P less than 0.05) in average IEMG-time curve and with the increase (P less than 0.05) in the FT:ST muscle fibre area ratio. The percentage of FT fibres of the muscle correlated (P less than 0.05) with the improvement of average force-time curve during the training. The increase in maximal force was accompanied by significant (P less than 0.05) increases in maximum IEMGs of the trained muscles. However, the hypertrophic changes, as judged from the anthropometric and muscle fibre area data, were only slight during the training. It can be concluded that in training for fast force production considerable neural and selective muscular adaptations may occur to explain the improvement in performance, but that genetic factors may determine the ultimate potential of the trainability of this aspect of the neuromuscular performance.