Reactive Strength as a Metric for Informing Return-to-Sport Decisions: A Case-Control Study.

OBJECTIVE: Current return-to-sport decisions are primarily based on elapsed time since surgery or injury and strength measures. Given data that show rates of successful return to competitive sport at around 55%, there is strong rationale for adopting tools that will better inform return to sport decisions. The authors' objective was to assess reactive strength as a metric for informing return-to-sport decisions. DESIGN: Case-control design. METHODS: Fifteen elite athletes from national sports teams (23 [6.0] y) in the final phase of their return-to-sport protocol following a unilateral knee injury and 16 age-matched control athletes (22 [4.6] y) performed a unilateral isometric strength test and 24-cm drop jump test. Pairwise comparisons were used to determine differences between legs within groups and differences in interleg asymmetry between groups. RESULTS: Strength measures did not distinguish the control from the rehabilitation group; however, clear differences in the degree of asymmetry were apparent between the control and rehabilitation groups for contact time (Cohen d = 0.56; -0.14 to 1.27; 8.2%; P = .113), flight time (d = 1.10; 0.44 to 1.76; 16.0%; P = .002), and reactive strength index (d = 1.27; 0.50 to 2.04; 22.4%; P = .002). CONCLUSION: Reactive strength data provide insight into functional deficits that persist into the final phase of a return-to-sport protocol. The authors' findings support the use of dynamic assessment tools to inform return-to-sport decisions to limit potential for reinjury.

Effectiveness of an Unexpected Disturbance Program in the Early Stage of Rehabilitation in Athletes With Unilateral Knee Ligament Injury.

CONTEXT: Sensorimotor, proprioceptive, and neuromuscular programs are critical for the successful rehabilitation of injured athletes, and these decrease reinjury rates. OBJECTIVE: To investigate the effects of an unexpected disturbance program (UDP) on balance and unilateral strength metrics in athletes with unilateral knee ligament injury. DESIGN: A 3-week parallel-group experimental design consisting of 9 rehabilitation sessions. SETTING: National Sports Institute. PARTICIPANTS: Twenty-one national-level athletes (age 21.4 [4.4] y, body mass 63.9 [10.8] kg, height 169.0 [10.2] cm) who had sustained a unilateral knee ligament injury. INTERVENTION: An UDP program designed to evoke rapid sensorimotor responses was compared with traditional training and a nonexercise control group. MAIN OUTCOME MEASURES: Unilateral total, anteroposterior, and mediolateral sway with eyes open and closed and unilateral isometric strength. RESULTS: Traditional exercises tended to outperform the UDP when unilateral balance testing was performed with eyes open; however, balance improvement following UDP tended to be greater in the eyes-closed condition. Significant strength gains in both the injured and uninjured legs were only observed following the UDP. This increase in unilateral isometric strength was 23.4 and 35.1 kg greater than the strength improvements seen in the traditional rehabilitation and control groups (P < .05). CONCLUSIONS: UDP could improve neural aspects of rehabilitation to improve rehabilitation outcomes by improving strength, sensorimotor function, and proprioception. Given the complementary adaptations, an UDP could provide an effective adjunct to traditional rehabilitation protocols and improve return-to-play outcomes.

Using stochastic resonance and strength training as part of a rehabilitation programme for recurrent low back pain treatment: a case study.

Low back pain (LBP) is a common disabling health problem that can cause decreased spine proprioception. Stochastic resonance (SR) can influence detection performance, besides improving patients with significant sensory deficits, but have not been thoroughly tested for LBP. This study aimed to examine the application of SR therapy (SRT) and strength training for LBP treatment. The subject was a resistance-trained male in his early thirties. His back pain was unbearable after a strength training session. Standard pain relief alleviated the pain but the LBP developed at a similar intensity after 4 weeks. SRT (4-5 sets ×90 sec, 30-sec rest interval, supine position) was prescribed along with other exercises for 3 weeks (phase 1), and followed by tailor-made strength training for 16 weeks (phase 2). The Oswestry Disability Index was 66.7% (interpreted as "crippled") prior to first SRT, and reduced to minimal levels of 15.6% and 6.7% after four and seven SRT sessions, respectively. Similarly, pain intensity was ranging from 5 to 9 (distracting-severe) of the Numeric Rating Scale (NRS-11) prior to the first session but this was reduced considerably after four sessions (NRS-11: 0-1). During phase 2, the patient performed without complaining of LBP, two repetitions of bench press exercise at a load intensity of 1.2 his body weight and attained 4 min of plank stabilisation. This LBP management strategy has a clinically meaningful effect on pain intensity, disability, and functional mobility, by receding the recurrent distracting to severe LBP.

Improvement of Elite Female Athletes' Physical Performance With a 3-Week Unexpected Disturbance Program.

CONTEXT: Sensorimotor training is commonly used in a rehabilitative setting; however, the effectiveness of an unexpected disturbance program (UDP) to enhance performance measures in uninjured elite athletes is unknown. OBJECTIVE: To assess the impact of a 3-wk UDP program on strength, power, and proprioceptive measures. DESIGN: Matched-group, pre-post design. SETTING: National sport institute. PARTICIPANTS: 21 international-level female field hockey athletes. INTERVENTION: Two 45-min UDP sessions were incorporated into each week of a 3-wk training program (total 6 sessions). MAIN OUTCOME MEASURES: 1-repetition-maximum strength, lower-limb power, 20-m running speed, and proprioception tests were performed before and after the experimental period. RESULTS: Substantial improvements in running sprint speed at 5-m (4.4 ± 2.6%; effect size [ES]: 0.88), 10-m (2.1 ± 1.9%; ES: 0.51), and 20-m (1.0 ± 1.6%; ES: 0.23) were observed in the UDP group. Squat-jump performance was also clearly enhanced when compared to the control group (3.1 ± 6.1%; ES: 0.23). Small but clear improvements in maximal strength were observed in both groups. CONCLUSIONS: A 3-wk UDP can elicit clear enhancements in running sprint speed and concentric-only jump performance. These improvements are suggestive of enhanced explosive strength and are particularly notable given the elite training status of the cohort and relatively short duration of the intervention. Thus, the authors would reiterate the statement by Gruber et al (2004) that sensorimotor training is a "highly efficient" modality for improving explosive strength.

Sensory-motor training targeting motor dysfunction and muscle weakness in long-term care elderly combined with motivational strategies: a single blind randomized controlled study.

BACKGROUND: This study evaluated the effects of a combined innovative training regime consisting of stochastic resonance whole-body vibration (SR-WBV) and a dance video game (DVG) on physical performance and muscle strength in long-term-care dwelling elderly. METHODS: Thirthy long-term-care elderly were randomly allocated to an intervention group (IG; n = 16) receiving combined SR-WBV training and DVG, or a sham group (SG; n = 14). IG performed five sets one minute of SR-WBV, with one minute rest between sets (base frequency 3 Hz up to 6 Hz, Noise 4) during the first five weeks on three days per week. From week five to eight a DVG was added to SR-WBV for IG on three days per week. SG performed a five-set SR-WBV program (1 Hz, Noise 1) lasting five times one minute, with one minute rest in between, three days a week. From week five to eight stepping exercises on a trampoline were added on three days per week. PRIMARY OUTCOME: Short physical performance battery (SPPB). Secondary outcome: isometric maximal voluntary contraction (IMVC), and sub phases of IMVC (Fsub), isometric rate of force development (IRFD) and sub time phases of IRFD (IRFDsub) were measured at baseline, after four and eight weeks. ANOVA with repeated measures was used for analyses of time and interaction effects and MANOVA determined between group intervention effects. RESULTS: Between group effects revealed significant effects on the SPPB primary outcome after four weeks F(1, 27) = 6.17; p = 0.02) and after eight weeks F(1,27) = 11.8; p = 0.002). Secondary muscle function related outcome showed significant between group effects in IG on IRFD, Fsub 30 ms, 100 ms, 200 ms and IRFDsub 0-30 ms, 0-50 ms, 0-100 ms and 100-200 ms compared to SG (all p < 0.05). CONCLUSIONS: Eight weeks SR-WBV and DVG intervention improved lower extremity physical function and muscle strength compared to a sham intervention in long-term-care elderly. SR-WBV and DVG seems to be effective as a training regime for skilling up in long-term-care elderly.

Unexpected-Disturbance Program for Rehabilitation of High-Performance Athletes.

CONTEXT: The Unexpected-Disturbance Program (UDP) promotes exercises in response to so-called involuntary short- to midlatency disturbances. OBJECTIVE: This study investigated the effectiveness of the UDP in the last 6 wk of rehabilitation. DESIGN: Pre-post study with 2-tailed paired t tests for limited a priori comparisons to examine differences. SETTING: National Sports Institute of Malaysia. PARTICIPANTS: 24 Malaysian national athletes. INTERVENTIONS: 7 sessions/wk of 90 min with 3 sessions allocated for 5 or 6 UDP exercises. MAIN OUTCOMES: Significant improvements for men and women were noted. Tests included 20-m sprint, 1-repetition-maximum single-leg press, standing long jump, single-leg sway, and a psychological questionnaire. RESULTS: For men and women, respectively, average strength improvements of 22% (d = 0.96) and 29% (d = 1.05), sprint time of 3% (d = 1.06) and 4% (d = 0.58), and distance jumped of 4% (d = 0.59) and 6% (d = 0.47) were noted. In addition, athletes reported improved perceived confidence in their abilities. All athletes improved in each functional test except for long jump in 2 of the athletes. Mediolateral sway decreased in 18 of the 22 athletes for the injured limb. CONCLUSION: The prevention training with UDP resulted in improved conditioning and seems to decrease mediolateral sway.

Feasibility and effects of applying stochastic resonance whole-body vibration on untrained elderly: a randomized crossover pilot study.

BACKGROUND: Aging is associated with loss of balance and activity in daily life. It impacts postural control and increases the risk of falls. The current study was conducted to determine the feasibility and long-term impact of stochastic resonance whole-body vibration (SR-WBV) on static and dynamic balance and reaction time among elderly individuals. METHODS: A randomized crossover pilot study with blinding of the participants. Twenty elderly were divided into group A (SR-WBV 5 Hz, Noise 4/SR-WBV 1 Hz, Noise 1) or group B (SR-WBV 1 Hz, Noise 1/SR-WBV 5 Hz, Noise 1). Feasibility outcomes included recruitment, compliance and safety. Secondary outcomes were Semi-Tandem Stand (STS), Functional Reach Test (FRT), Expanded Timed Get Up-and-Go (ETGUG), walking under single (ST) & dual task (DT) conditions, hand and foot reaction time (RTH/RTF). Puri and Sen Rank-Order L Statistics were used to analyse carry-over effects. To analyse SR-WBV effects Wilcoxon signed-ranked tests were used. RESULTS: With good recruitment rate (55%) and compliance (attrition 15%; adherence 85%) rates the intervention was deemed feasible. Three participants dropped out, two due to knee pain and one for personal reasons. ETGUG 0 to 2 m (p = 0.143; ES: 0.36) and ETGUG total time (p = 0.097; ES: 0.40) showed medium effect sizes. CONCLUSIONS: Stochastic resonance training is feasible in untrained elderly resulting in good recruitment and compliance. Low volume SR-WBV exercises over 12 training sessions with 5 Hz, Noise 4 seems a sufficient stimulus to improve ETGUG total time. The stimulation did not elicit changes in other outcomes. TRIAL REGISTRATION: This trial has been registered at the U.S. National Institutes of Health under ClinicalTrials.gov: NCT01045746.

Preliminary inconclusive results of a randomised double blinded cross-over pilot trial in long-term-care dwelling elderly assessing the feasibility of stochastic resonance whole-body vibration.

BACKGROUND: This randomised double-blinded controlled cross-over pilot study examined feasibility and preliminary effects of stochastic resonance whole-body vibration training applied in long term care elderly. FINDINGS: Nine long term care elderly were recruited and randomized to group A (6 Hz, Noise 4 SR-WBV/ Sham) or B (Sham / 1 Hz, Noise 1 SR-WBV). Feasibility outcomes included recruitment rate, attrition, adherence and safety. Physical performance outcomes focused on the Expanded Timed Get Up-and-Go (ETGUG) test, the Short Physical Performance Battery (SPPB), and lower extremity muscle strength. Of 24 subjects initially approached 9 started and 5 completed the study resulting in 37.5 recruitment, 44.4 attrition and 81.7 % adherence rates. No adverse events were reported. There is more evidence of improved performance levels in the SR-WBV treatment group with significant differences in average change for isometric rate of force development (p = 0.016 left leg; p = 0.028 right leg). No statistical significance was reached for other parameters. CONCLUSIONS: The findings of this study indicate that the used training protocol for long term care elderly is feasible, however, requires more closely monitoring of participants; e.g. needs protocol modifications that target improved compliance with the intervention in this setting. SR-WBV shows beneficial effects on physical performance for those adhering to the intervention. TRIAL REGISTRATION: U.S. National Institutes of Health NCT01543243.

Immediate effects after stochastic resonance whole-body vibration on physical performance on frail elderly for skilling-up training: a blind cross-over randomised pilot study.

OBJECTIVE: This pilot study examined the feasibility outcome recruitment, safety and compliance of the investigation for stochastic resonance whole-body vibration (SR-WBV) training. Another aim was to evaluate the effect size of one SR-WBV intervention session on Short Physical Performance Battery (SPPB), Expanded Timed Get Up-and-Go (ETGUG), isometric maximal voluntary contraction (IMVC) and rate of force development (IRFD) and chair rising (CR). DESIGN: Randomised double-blinded controlled cross-over pilot study. METHOD: Feasibility outcomes included recruitment, safety and compliance. For secondary outcomes, SPPB, ETGUG, IMVC, IRFD and CR were measured before and 2-min after intervention. Nonparametric Rank-Order Tests of Puri and Sen L Statistics to Ranked Data were proposed. Wilcoxon signed-ranked tests were used to analyse the differences after SR-WBV intervention and sham intervention. Treatment effects between the interventions were compared by a Mann-Whitney U test. RESULTS: Among 24 eligible frail elderly, 12 agreed to participate and 3 drop out. The adherence was 15 of 24 intervention sessions. For secondary outcome, effect sizes (ES) for SR-WBV intervention on SPPB, ETGUG and CR were determined. CONCLUSION: This pilot study indicate that the training protocol used in this form for frail elderly individuals is feasible but with modification due to the fact that not all defined feasibility outcomes target was met. SR-WBV with 6 Hz, noise level 4 shows benefit improvements on SPPB (ES 0.52), ETGUG (part sit-to-stand movement: ES 0.81; total time: ES 0.85) and CR (ES 0.66). Further research is desired to determine whether a new adapted training protocol is necessary for SR-WBV in the "skilling up" phase in frail elderly individuals.

Long-term strength training effects on change-of-direction sprint performance.

The requirement profiles for sports such as soccer, football, tennis, and rugby demonstrate the importance of strength and speed-strength abilities, in addition to other conditional characteristics. During a game, the athletes complete a large number of strength and speed-strength actions. In addition to the linear sprints, athletes perform sprints while changing the direction (change-of-direction sprint [COD]). Therefore, this study aims to clarify the extent to which there is a strength training intervention effect on COD. Further, this investigation analyzes the possible correlations between the 1-Repetition Maximum/body mass (SREL) in the front and back squats and COD. The subjects (n = 112) were at pretest between 13 and 18 years of age and were divided into 2 groups with 4 subgroups (A = under 19 years of age, B = under 17 years of age, and C = under 15 years of age). For approximately 2 years, 1 group (control group [CG]) only participated in routine soccer training, and the other group (strength training group [STG]) participated in an additional strength training program with the routine soccer training. Additionally, the performances in the COD of 34 professional soccer players of the first and second divisions in Germany were measured as a standard of high-level COD. For the analysis of the performance development within a group and pairwise comparisons between 2 groups, an analysis of variance with repeated measures was calculated with the factors group and time. Relationships between the COD and SREL were calculated for the normal distributed data using a plurality of bivariate correlations by Pearson. Our data show that additional strength training over a period of 2 years significantly affects the performance in the COD. The STG in all subcohorts reached significantly (p < 0.05) faster times in the COD than did the CG. The STG amounted up to 5% to nearly 10% better improvements in the 10-m sprint times compared with that of the CG. Furthermore, our data show significant (p < 0.05) moderate to high correlations (r = -0.388 to -0.697) between the SREL and COD. Our data show that a long-term strength training improves the performance of the COD. Therefore, a long-term resistance training is recommended as early as in childhood and adolescence.

Influence of a 2-year strength training programme on power performance in elite youth soccer players.

In soccer, strength, power and speed are very important because of the large number of power actions performed during the game. Therefore, the aim of this study was to examine the influence of periodised strength training for power performance more than 2 years. In this study, 134 elite youth soccer players were recruited from two youth training centres. The cohorts were arranged as follows: A (under 19 years), B (under 17 years) and C (under 15 years). The participants in each cohort were divided into two groups. One group (Strength training group [STG]) was subjected to regular soccer training in addition to strength training twice a week for 2 years. The other group (Control group [CG]) completed only the regular soccer training. The strength training was periodised with hypertrophy and intramuscular coordination blocks. For strength training, both the front squat and the back squat were performed once a week. The subjects were tested on the one-repetition maximum (1RM) of the front and back squat and a linear sprint over 30 m. There was significantly better performance from the STG on 1RM (p <0.001). In the sprint, the STG displayed significantly better improvements (p <0.05 to p <0.001) of up to 6%. The effects of strength training are reflected in the sprint performance. Therefore, it seems beneficial for youth to perform strength training to exploit the reserve capacity in sprint performances.

Static stretching of the hamstring muscle for injury prevention in football codes: a systematic review.

PURPOSE: Hamstring injuries are common among football players. There is still disagreement regarding prevention. The aim of this review is to determine whether static stretching reduces hamstring injuries in football codes. METHODS: A systematic literature search was conducted on the online databases PubMed, PEDro, Cochrane, Web of Science, Bisp and Clinical Trial register. Study results were presented descriptively and the quality of the studies assessed were based on Cochrane's 'risk of bias' tool. RESULTS: The review identified 35 studies, including four analysis studies. These studies show deficiencies in the quality of study designs. CONCLUSION: The study protocols are varied in terms of the length of intervention and follow-up. No RCT studies are available, however, RCT studies should be conducted in the near future.

Is there a difference between active and less active children and adolescents in jump performance?

Training and activity level are important predictors of motor development. At present, many children and adolescents do not participate in any sport activity in their leisure time. In this investigation, we analyzed the level of performance of the stretch and shortening cycle (SSC) in childhood and youth. Data of 801 participants were recorded for 2 separate groups, those in elite soccer associations and those who were less active in their leisure time. All the participants completed the following performance tests: the squat jump, the countermovement jump and the drop jump from varying heights. All the participants answered a questionnaire to determine their level of activity. Comparisons of performance were made across the 2 groups. The data showed a significant (p < 0.05) advantage for soccer players in nearly every variable involved in the performance of the SSC. The analysis of the questionnaire highlights the fact that approximately a quarter of students are inactive in their leisure time, which means they do not participate in any sport activity except for school sports. The data show that many children and adolescents do not participate in sport activities in their leisure time. Furthermore, many of these children and adolescents have a body mass index >25. The results of this investigation support the fact that inactivity is correlated with a low training level in children and youth.

Effects of functional exercises in the warm-up on sprint performances.

The process of warming up prepares athletes for subsequent stress and increases their level of performance. Functional exercises are often included in warm-up programs for power sports, although a positive effect of functional exercises has not been confirmed. The aim of this study was to measure a possible effect of functional exercises on sprint performance included in a warm-up program. A total of 121 elite youth soccer players between 13 and 18 years of age participated in this study and performed 2 different warm-up programs. The first program (NWP) consisted of 5 minutes of nonspecific running, coordination exercises, stretching, and acceleration runs. The second program (WPS) was the same with additional functional exercises. The subjects were tested performing linear sprints of approximately 30 m and change-of-direction sprints of approximately 10 m. The t-test for dependent samples showed significant differences between the groups for each segment of the linear sprint (p < 0.01 for 5 m; p < 0.001 for 10, 15, 20, 25, and 30 m); however, the effect sizes are small. Also, in the change-of-direction sprint, the t-test showed significant differences between the groups (p < 0.01 for 10 m left, 10 m right; p < 0.001 for 5 m right). These effect sizes are also small. In the change-of-direction sprint time for 5 m left, the data showed no significant differences between the groups. The results show no effects of functional exercises on sprint performance that are implemented in addition to a general warm-up. It appears that a general warm-up program, such as the NWP, generates sufficient activation of the performance-limiting muscles for sprint performance. Functional exercises did not lead to a supplemental activation with a positive effect on sprint performance. Therefore, a warm-up for sprint performance should contain nonspecific running, coordination exercises, stretching exercises, and acceleration runs. These components lead to sufficient activation of the muscles involved in sprint performance. Coaches should use the limited time available for warm-up to work efficiently. The recommendation for warm-up is to pass on functional exercises that have no additional effect in enhancing performance.

Influence of squatting depth on jumping performance.

It is unclear if increases in 1 repetition maximum (1RM) in quarter squats result in higher gains compared with full depth squats in isometric force production and vertical jump performance. The aim of the research projects was to compare the effects of different squat variants on the development of 1RM and their transfer effects to Countermovement jump (CMJ) and squat jump (SJ) height, maximal voluntary contraction (MVC), and maximal rate of force development (MRFD). Twenty-three women and 36 men (mean age: 24.11 ± 2.88 years) were parallelized into 3 groups based on their CMJ height: deep front squats (FSQ, n = 20), deep back squats (BSQ, n = 20), and quarter back squats (BSQ», n = 19). In addition, a control group (C, n = 16) existed (mean age: 24.38 ± 0.50 years). Experimental groups trained 2 d·wk for 10 weeks with a strength-power block periodization, which produced significant (p ≤ 0.05) gains of the specific squat 1RM. The FSQ and BSQ attained significant (p ≤ 0.05) elevations in SJ and CMJ without any interaction effects between both groups (p ≥ 0.05). The BSQ» and C did not reveal any significant changes of SJ and CMJ. The FSQ and BSQ had significantly higher SJ scores over C (p ≤ 0.05). The BSQ did not feature any significant group difference to BSQ» (p = 0.116) in SJ, whereas FSQ showed a trend toward higher SJ heights over BSQ» (p = 0.052). The FSQ and BSQ presented significantly (p ≤ 0.05) higher CMJ heights over BSQ» and C. Posttest in MVC and MRFD demonstrated no significant changes for BSQ. Significant declines in MRFD for FSQ in the right leg (p ≤ 0.05) without any interaction effects for MVC and MRFD between both FSQ and BSQ were found. Training of BSQ» resulted in significantly (p ≤ 0.05) lower MRFD and MVC values in contrast to FSQ and BSQ. Quarter squat training elicited significant (p ≤ 0.05) transfer losses into the isometric maximal and explosive strength behavior. These findings therefore contest the concept of superior angle-specific transfer effects. Deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared with quarter squats.

Training effects of two different unstable shoe constructions on postural control in static and dynamic testing situations.

OBJECTIVE: The aim of this study was to compare training effects on postural control using two different unstable shoe constructions. SUBJECTS AND SETTING: Twenty-nine healthy subjects participated in this study and were randomly divided into three groups. Two experimental groups (10 subjects in each group) were assigned to a 6 week training program of specific sensorimotor exercises with unstable shoe constructions, one group using MBT(®) shoes and one group wearing Reflex Control(®) shoes (RC). Subjects in the control group (9 subjects) did not perform balance training. MAIN OUTCOME MEASURES: Postural control was measured in one-leg stance in two testing conditions. We recorded postural sway on a force plate (static testing situation) and displacements of a moveable platform (dynamic testing situation) before and after the training period. RESULTS: There were no effects of training with unstable shoe constructions on postural sway in the static testing condition (for comparison of groups: p = 0.990 and p = 0.119). However, the RC group showed statistically significant improvements in the dynamic testing situation (p = 0.014 compared to control subjects). In the MBT group improvements were not significantly different in comparison to control group (p = 0.518). CONCLUSIONS: Our results indicate that exercises using unstable shoe constructions, particularly the RC, improve postural control only in dynamic conditions.

Outcome effects of single-set versus multiple-set training--an advanced replication study.

The starting point of this review is the assumption that single-set training (SST) can be regarded as an equal alternative to multiple-set strength training. On the basis of 72 primary studies, the meta-analysis dealt with the problem of single-set vs. multiple-set training (MST). The effectiveness of these training methods was examined depending on various interventions. Apart from qualitative decision aspects, the effectiveness was checked on the basis of effect size. Generally speaking, it can be stated that MST, depending on factors like age, training experience, duration of the study, etc., offers several advantages over single-set regimes (F = 3.71; df = 1; p = 0.06; eta(2) = 0.02), especially when combined with periodization strategies, and it can be applied very successfully for increasing maximal strength in long-time effects. Therefore, the outcome effects of both methods are the same in short-time interventions. For longer-time interventions (F = 15.74; df = 1; p < 0.05; eta(2) = 0.12) and for advanced subjects with the goal of optimizing their strength gain, however, multiple-set strategies are superior (F = 7.32; df = 1; p < 0.05; eta(2) = 0.06).

Effects of heavy resistance training on strength and power in upper extremities in wheelchair athletes.

Little is known about strength training in subjects with spinal cord injury (SCI), especially in athletes performing competitive sports. Sixteen male subjects participated in this study-8 with SCI and 8 healthy physical education students (control subjects). The 8-week program consisted of heavy-resistance exercise performed twice per week with 10 to 12 repetitions in 5 sets. Subjects' performances were tested in static and in dynamic conditions concerning several strength and power parameters. Furthermore, we tested 10-m sprinting performance in wheelchair athletes. Overall, wheelchair athletes and control subjects achieved similar results; in almost all parameters both groups improved considerably in post-testing. Regarding percentages in most strength and power parameters, wheelchair athletes showed a tendency to benefit more from the strength training performed in the present study. Using analyses of group differences, however, only the comparison of effects on rate of force development (p = 0.010) resulted in a significant higher improvement for wheelchair athletes. In contrast to previous assumptions about minor adaptation capacities to training exercises in patients with SCI, our study proved clear effects of strength training. In conclusion, we suggest that heavy resistance training should be of increasing importance in wheelchair sports.

Effects of different periodization models on rate of force development and power ability of the upper extremity.

The purpose of our study was to compare the effects of 2 different periodization models on strength and power variables under dynamic and static conditions in the bench press. Participants of the experimental groups were male sport students experienced in weight training (age: 23.98 +/- 3.14 yr). Subjects were tested for the 1 repetition maximum (1RM) in the bench press, maximal movement velocity (Vmax) in the bench press throw (16.9 kg), maximal voluntary contraction (MVC), and maximal rate of force development (MRFD) in 90 degrees elbow and shoulder angle in the isometric bench press. According to their 1RM, subjects were parallelized and assigned to 1 of either 2 training groups: strength-power periodization (SPP, n = 13) or daily undulating periodization (DUP, n = 14). Subjects trained for 14 weeks, 3 days per week. In the strength-power sessions, both groups were instructed to lift the weight as explosively as possible. In addition, a control group (n = 13) was used for comparison. One repetition maximum and Vmax improved significantly through training (p

Skeletal muscle IL-4, IL-4Ralpha, IL-13 and IL-13Ralpha1 expression and response to strength training.

Interleukin-4 (IL-4) and interleukin-13 (IL-13) are Th2 cytokines involved in various immune responses and only a few reports examine skeletal muscle and the possible role of Th2 cytokines in myoblast fusion and myotube maturation. We hypothesized that IL-4, IL-13 and their receptors are involved in skeletal muscle adaptations to strength training. We investigated the effects of 6 weeks of strength training with different muscle load on IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression in skeletal muscle: training with maximal contractions (Max group, n = 12) and training with lower load combined with ballistic and stretch-shortening contractions (Combi group, n = 12). Muscle samples were taken from triceps brachii before and after the 6 weeks of training. mRNA levels of IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 expression were determined by real-time PCR and IL-4 protein expression by ELISA. We demonstrate for the first time that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are expressed in skeletal muscle in vivo and are up-regulated after strength training. Higher training load in Max leads to higher cytokine responses, which was significant for IL-4Ralpha though IL-4 protein expression did not change significantly. Although the exact mechanisms have yet to be established, and these results may be preliminary, we speculate that IL-4, IL-13, IL-4Ralpha and IL-13Ralpha1 are involved in muscle hypertrophy, MHC-transformation and anti-inflammatory damage control that occur during strength training.