Contralateral effects of unilateral strength training: evidence and possible mechanisms.

If exercises are performed to increase muscle strength on one side of the body, voluntary strength can increase on the contralateral side. This effect, termed the contralateral strength training effect, is usually measured in homologous muscles. Although known for over a century, most studies have not been designed well enough to show a definitive transfer of strength that could not be explained by factors such as familiarity with the testing. However, an updated meta-analysis of 16 properly controlled studies (range 15-48 training sessions) shows that the size of the contralateral strength training effect is approximately 8% of initial strength or about half the increase in strength of the trained side. This estimate is similar to results of a large, randomized controlled study of training for the elbow flexors (contralateral effect of 7% initial strength or one-quarter of the effect on the trained side). This is likely to reflect increased motoneuron output rather than muscular adaptations, although most methods are insufficiently sensitive to detect small muscle contributions. Two classes of central mechanism are identified. One involves a "spillover" to the control system for the contralateral limb, and the other involves adaptations in the control system for the trained limb that can be accessed by the untrained limb. Cortical, subcortical and spinal levels are all likely to be involved in the "transfer," and none can be excluded with current data. Although the size of the effect is small and may not be clinically significant, study of the phenomenon provides insight into neural mechanisms associated with exercise and training.     

Hypertrophic response to unilateral concentric isokinetic resistance training.

The purposes of this study were to 1) determine the effect of concentric isokinetic training on strength and cross-sectional area (CSA) of selected extensor and flexor muscles of the forearm and leg, 2) examine the potential for preferential hypertrophy of individual muscles within a muscle group, 3) identify the location (proximal, middle, or distal level) of hypertrophy within an individual muscle, and 4) determine the effect of unilateral concentric isokinetic training on strength and hypertrophy of the contralateral limbs. Thirteen untrained male college students [mean age 25.1 +/- 6.1 (SD) yr] volunteered to perform six sets of 10 repetitions of extension and flexion of the nondominant limbs three times per week for 8 wk, using a Cybex II isokinetic dynamometer. Pretraining and posttraining peak torque and muscle CSA measurements for both the dominant and nondominant limbs were determined utilizing a Cybex II isokinetic dynamometer and magnetic resonance imaging scanner, respectively. The results indicated significant (P less than 0.0008) hypertrophy in all trained muscle groups as well as preferential hypertrophy of individual muscles and at specific levels. None of the muscles of the contralateral limbs increased significantly in CSA. In addition, significant (P less than 0.0008) increases in peak torque occurred for trained forearm extension and flexion as well as trained leg flexion. There were no significant increases in peak torque, however, for trained leg extension or for any movement in the contralateral limbs. These data suggest that concentric isokinetic training results in significant strength and hypertrophic responses in the trained limbs.     

Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises

The primary objective of this investigation was to identify which components of endurance training (e.g., modality, duration, frequency) are detrimental to resistance training outcomes. A meta-analysis of 21 studies was performed with a total of 422 effect sizes (ESs). Criteria for the study included were (a) compare strength training alone to strength plus endurance training (concurrent) or to compare combinations of concurrent training; (b) the outcome measures include at least one measure of strength, power, or hypertrophy; and (c) the data necessary to calculate ESs must be included or available. The mean ES for hypertrophy for strength training was 1.23; for endurance training, it was 0.27; and for concurrent training, it was 0.85, with strength and concurrent training being significantly greater than endurance training only. The mean ES for strength development for strength training was 1.76; for endurance training, it was 0.78; and for concurrent training, it was 1.44. Strength and concurrent training was significantly greater than endurance training. The mean ES for power development for strength training only was 0.91; for endurance training, it was 0.11; and for concurrent training, it was 0.55. Significant differences were found between all the 3 groups. For moderator variables, resistance training concurrently with running, but not cycling, resulted in significant decrements in both hypertrophy and strength. Correlational analysis identified significant negative relationships between frequency (-0.26 to -0.35) and duration (-0.29 to -0.75) of endurance training for hypertrophy, strength, and power. Significant relationships (p < 0.05) between ES for decreased body fat and % maximal heart rate (r = -0.60) were also found. Our results indicate that interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected.     

Lateral specificity in resistance training: the effect of bilateral and unilateral training

 Maximal voluntary strength of simultaneous bilateral exertion has been shown to be small compared to the sum of the unilateral exertions. Three experiments were conducted to determine the effects of bilateral and unilateral resistance training on this bilateral deficit and to compare these in hands, arms, and legs. In each experiment, the subjects were divided into three groups: unilateral training group, bilateral training group, and control group. The subjects of the training group performed maximal isometric handgrip training in experiment I, and maximal isokinetic arm and leg extension training in experiments II and III. In each experiment, the subjects of the training group continued one of these resistance training exercises three times a week, for 6 weeks. The increase in handgrip strength of the bilateral training group produced in the bilateral condition [5.1 (SEM 2.4)%, after 3 weeks, 6.4 (SEM 2.3) %, after 6 weeks] was significantly greater compared with the control group [−1.1 (SEM 1.0) %, after 3 weeks, −1.5 (SEM 1.1) %, after 6 weeks. The increase in leg extension power of the bilateral training group produced in the bilateral condition [16.1 (SEM 9.6) %, after 3 weeks, 24.1 (SEM 7.4) %, after 6 weeks] was significantly greater compared with the unilateral training group [−5.0 (SEM 3.4) %, after 3 weeks, −3.4 (SEM 4.2) %, after 6 weeks] and the control group [−4.3 (SEM 2.5) %, after 3 weeks, 1.5 (SEM 5.5) %, after 6 weeks]. The increase in handgrip strength of the unilateral training group produced in the unilateral condition [7.3 (SEM 1.7) %, after 3 weeks] was significantly greater compared with the control group [−0.9 (SEM 1.8) %, after 3 weeks]. The increase in arm extension power of the unilateral training group produced in the unilateral condition [7.2 (SEM 1.8) %, after 6 weeks] was significantly greater compared with the bilateral training group [−3.0 (SEM 2.3) %, after 6 weeks] and the control group [−2.1 (SEM 2.6) %, after 6 weeks]. Bilateral indexes (BI) were shifted in a positive direction by bilateral training and tended to shift in a negative direction by unilateral training. With regard to the magnitude of change in BI, there were no significant differences among handgrip, arm extension, and leg extension training. It is suggested that there is lateral specificity in resistance training and that there is no difference among body parts in the modification of bilateral deficit by lateral training. Accepted: 27 August 1996     

The effects of plyometric training on sprint performance: a meta-analysis

The purpose of this meta-analysis was to attempt to gain a clear picture of the magnitude of sprint performance improvements expected after chronic plyometric training (PT) and to identify specific factors that influence the treatment effects. Studies employing a PT intervention and containing data necessary to calculate effect size (ES) were included in the analysis. A total of 26 studies with a total of 56 ES met the inclusion criterion. Analysis of ES demonstrated that the strategies that seem to maximize the probability of obtaining significantly (p < 0.05) greater improvement in sprint performance included training volume for <10 weeks; a minimum of 15 sessions; and high-intensity programs with >80 combined jumps per session. To optimize sprint enhancement, the combination of different types of plyometrics and the use of training programs that incorporate greater horizontal acceleration (i.e., sprint-specific plyometric exercises, jumps with horizontal displacement) would be recommended, rather than using only one form of jump training (p < 0.05). No extra benefits were found to be gained from doing plyometrics with added weight. The loading parameters identified in this analysis should be considered by the professional sprinters and specialized trainers with regard to the most appropriate dose-response trends PT to optimized sprint performance gains.     

Effects of unilateral vs. bilateral resistance training interventions on measures of strength,jump, linear and change of direction speed: a systematic review and meta-analysis

Exercises can be categorized into either unilateral or bilateral movements. Despite the topic popularity, the answer to the question as to which (unilateral or bilateral) is superior for a certain athletic performance enhancement remains unclear. To compare the effect of unilateral and bilateral resistance training interventions on measures of athletic performance. Keywords related with unilateral, bilateral and performance were used to search in the Web of Science, PubMed databases, and Google Scholar and ResearchGate™ websites. 6365 articles were initially identified, 14 met the inclusion criteria and were included in the final analysis, with overall article quality being deemed moderate. The quantitative analysis comprised 392 subjects (aged: 16 to 26 years). Sub-group analysis showed that unilateral exercise resistance training resulted in a large effect in improving unilateral jump performance compared to bilateral training (ES = 0.89 [0.52, 1.26]). In contrast, bilateral exercise resistance training showed a small effect in improving bilateral strength compared to unilateral (ES = -0.43 [-0.71, -0.14]). Non-significant differences were found in improving unilateral strength (ES = 0.26 [-0.03, 0.55]), bilateral jump performance (ES = -0.04 [-0.31, 0.23]), change of direction (COD) (ES = 0.31 [-0.01, 0.63]) and speed (ES = -0.12 [-0.46, 0.21]) performance. Unilateral resistance training exercises should be chosen for improving unilateral jumping performance, and bilateral resistance training exercises should be chosen for improving bilateral strength performance.     

The effects of short-term unilateral and bilateral lower-body resistance training on measures of strength and power

The purpose of this study was to compare the effects of short-term unilateral resistance training (UL) and bilateral resistance training (BL) with free weights on several tests of unilateral and bilateral lower-body strength and power in men and women. Thirty-eight untrained men and women (mean body mass 78.3 +/- 21.47 kg; age 20.74 +/- 2.6 years) completed the study. The groups trained 2 days per week for 8 weeks with free weights and 2 days per week for 5 of the 8 weeks with plyometric drills. The resistance-training program consisted of a progression from 3 sets of 15 repetitions at 50% of the subject's predicted 1 repetition maximum (1RM) to 6 sets of 5 repetitions at 87% 1RM. Training volume and intensity were equal for each group. The free-weight squat was used to measure unilateral and bilateral strength. Power was measured by the Magaria-Kalamen stair-climb test and the unilateral and bilateral vertical jump test. Analysis of covariance was used to analyze differences between men and women and the interaction of group and gender. Pretest scores were used as the covariate. The UL group improved more than the BL group on the unilateral vertical jump height (p = 0.001) and relative power (p = 0.013). After adjusting for pretest differences, the improved scores on all tests, except for the unilateral squat, were similar between the men and the women. No significant interactions on all tests were found for the men or women comparison between training groups. These results indicate that UL and BL are equally effective for early phase improvement of unilateral and bilateral leg strength and power in untrained men and women.     

Autogenic training: a meta-analysis of clinical outcome studies

Autogenic training (AT) is a self-relaxation procedure by which a psychophysiological determined relaxation response is elicited. A meta-analysis was performed to evaluate the clinical effectiveness of AT. Seventy-three controlled outcome studies were found (published 1952–99). Sixty studies (35 randomized controlled trials [RCT]) qualified for inclusion in the meta-analysis. Medium-to-large effect sizes (ES) occurred for pre–post comparisons of disease-specific AT-effects, with the RCTs showing larger ES. When AT was compared to real control conditions, medium ES were found. Comparisons of AT versus other psychological treatment mostly resulted in no effects or small negative ES. This pattern of results was stable at follow-up. Unspecific AT-effects (i.e., effects on mood, cognitive performance, quality of life, and physiological variables) tended to be even larger than main effects. Separate meta-analyses for different disorders revealed a significant reduction of the heterogeneity of ES. Positive effects (medium range) of AT and of AT versus control in the meta-analysis of at least 3 studies were found for tension headache/migraine, mild-to-moderate essential hypertension, coronary heart disease, asthma bronchiale, somatoform pain disorder (unspecified type), Raynaud's disease, anxiety disorders, mild-to-moderate depression/dysthymia, and functional sleep disorders.     

Neural inhibition during maximal eccentric and concentric quadriceps contraction: effects of resistance training.

Despite full voluntary effort, neuromuscular activation of the quadriceps femoris muscle appears inhibited during slow concentric and eccentric contractions. Our aim was to compare neuromuscular activation during maximal voluntary concentric and eccentric quadriceps contractions, hypothesizing that inhibition of neuromuscular activation diminishes with resistance training. In 15 men, pretraining electromyographic activity of the quadriceps muscles [vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF)] was 17-36% lower during slow and fast (30 and 240 degrees/s) eccentric and slow concentric contractions compared with fast concentric contractions. After 14 wk of heavy resistance training, neuromuscular inhibition was reduced for VL and VM and was completely removed for RF. Concurrently, electromyographic activity increased 21-52, 22-29, and 16-32% for VL, VM, and RF, respectively. In addition, median power frequency decreased for VL and RF. Eccentric quadriceps strength increased 15-17%, whereas slow and fast concentric strength increased 15 and 8%, respectively. Pre- and posttraining median power frequency did not differ between eccentric and concentric contractions. In conclusion, quadriceps motoneuron activation was lower during maximal voluntary eccentric and slow concentric contractions compared with during fast concentric contraction in untrained subjects, and, after heavy resistance training, this inhibition in neuromuscular activation was reduced.     

Contralateral neuro-motor apparatus under unilateral restriction of motor activity in rat

Electromyographic recordings of contralateral m. gastrocnemius of the rat after unilateral section of Achilles' tendon (tenotomy) were studied. Motor reflex, Hoffman reflex and firing of motor units of contralateral m. gastrocnemius were recorded in control and in 10 days after tendotomy. Motor units changed their firing in the background and in reaction to sciatic nerve stimulation. The results of study showed that unilateral section of Achilles' tendon increased the excitability of single motoneurons of contralateral spinal senters.     

The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: A systematic review and meta-analysis

The present paper endeavored to elucidate the topic on the effects of morning versus evening resistance training on muscle strength and hypertrophy by conducting a systematic review and a meta-analysis of studies that examined time of day-specific resistance training. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines with searches conducted through PubMed/MEDLINE, Scopus, and SPORTDiscus databases. The Downs and Black checklist was used for the assessment of the methodological quality of the included studies. Studies that examined the effects of time of day-specific resistance training (while equating all other training variables, such as training frequency and volume, between the groups) on muscle strength and/or muscle size were included in the present review. The random effects model was used for the meta-analysis. Meta-analyses explored (1) the differences in strength expression between morning and evening hours at baseline; (2) the differences in strength within the groups training in the morning and evening by using their post-intervention strength data from the morning and evening strength assessments; (3) the overall differences between the effects of morning and evening resistance training (with subgroup analyses conducted for studies that assessed strength in the morning hours and for the studies that assessed strength in the evening hours). Finally, a meta-analysis was also conducted for studies that assessed muscle hypertrophy. Eleven studies of moderate and good methodological quality were included in the present review. The primary findings of the review are as follows: (1) at baseline, a significant difference in strength between morning and evening is evident, with greater strength observed in the evening hours; (2) resistance training in the morning hours may increase strength assessed in the morning to similar levels as strength assessed in the evening; (3) training in the evening hours, however, maintains the general difference in strength across the day, with greater strength observed in the evening hours; (4) when comparing the effects between the groups training in the morning versus in the evening hours, increases in strength are similar in both groups, regardless of the time of day at which strength assessment is conducted; and (5) increases in muscle size are similar irrespective of the time of day at which the training is performed.     

Antioxidant enzyme activity is up-regulated after unilateral resistance exercise training in older adults

Cellular antioxidant capacity and oxidative stress are postulated to be critical factors in the aging process. The effects of resistance exercise training on the level of skeletal muscle oxidative stress and antioxidant capacity have not previously been examined in older adults. Muscle biopsies from both legs were obtained from the vastus lateralis muscle of 12 men 71 +/- 7 years of age. Subjects then engaged in a progressive resistance exercise-training program with only one leg for 12 weeks. After 12 weeks, the nontraining leg underwent an acute bout of exercise (exercise session identical to that of the trained leg at the same relative intensity) at the same time as the last bout of exercise in the training leg. Muscle biopsies were collected from the vastus lateralis of both legs 48 h after the final exercise bout. Electron transport chain enzyme activity was unaffected by resistance training and acute resistance exercise (p < 0.05). Training resulted in a significant increase in CuZnSOD (pre--7.2 +/- 4.2, post--12.6 +/- 5.6 U.mg protein(-1); p = 0.02) and catalase (pre--8.2 +/- 2.3, post--14.9 +/- 7.6 micromol.min(-1).mg protein(-1); p = 0.02) but not MnSOD activity, whereas acute exercise had no effect on the aforementioned antioxidant enzyme activities. Furthermore, basal muscle total protein carbonyl content did not change as a result of exercise training or acute exercise. In conclusion, unilateral resistance exercise training is effective in enhancing the skeletal muscle cellular antioxidant capacity in older adults. The potential long-term benefits of these adaptations remain to be evaluated.     

Effects of leucine and whey protein supplementation during eight weeks of unilateral resistance training

The purpose of this study was to determine the effects of resistance training in combination with a leucine and whey protein supplement or a carbohydrate placebo on strength and muscle cross-sectional area (CSA). Thirty-three men (mean age +/- SD = 22.4 +/- 2.4 years) were assigned to 1 of 3 groups: (1) supplementation group (SUPP), (2) placebo group (PL), or (3) control group (CON). The SUPP and PL performed unilateral training of the leg extensor muscles with the nondominant limb for 8 weeks. The strength of each limb, muscle CSA of the quadriceps femoris (QF), and body composition were assessed pretraining and posttraining. The results indicated significant increases in strength for both limbs in the SUPP but only the trained limb in the PL. The increase in strength for the trained limb of the SUPP was greater than that for the trained limb of the PL. There was no significant increase in strength for either limb in the CON. There were significant increases in the CSA of all muscles of the QF of the trained limb for the SUPP and PL, and of the vastus lateralis of the untrained limb for the SUPP. The increases in QF CSA did not differ between the SUPP and PL. No significant CSA changes were found for either limb in the CON. There were no significant changes in body composition for the SUPP, PL, or CON. The current findings suggest that leucine and whey protein supplementation may provide an ergogenic effect which enhances the acquisition of strength beyond that achieved with resistance training and a carbohydrate placebo.     

High resistance/low repetition vs. low resistance/high repetition training: effects on performance of trained cyclists

In order to investigate the effects of a resistance training modality on cycling performance, 23 trained club-level cyclists were placed into high resistance/low repetition (H-Res), low resistance/high repetition (H-Rep), or cycling-only groups for a 10-week program. All 3 groups followed the same cycling plan, but the H-Res and H-Rep groups added resistance training. Testing pre and post consisted of a graded incremental lactate profile test on an ergometer, with blood lactate being sampled. VO2 values were measured to determine economy. Maximum strength testing of 4 strength exercises targeting the lower extremity musculature was conducted with the H-Res and H-Rep groups. There were significant gains in all 4 resistance training exercises (p < 0.05) for both H-Res and H-Rep, with the H-Res group having significantly greater gains than the H-Rep group had in the leg press exercise (p < 0.05). There were, however, no significant group x training differences (p > 0.05) found between the 3 training groups on the cycling test in lactate values or economy. It appears that for this population of cyclists, neither H-Res nor H-Rep resistance training provided any additional performance benefit in a graded incremental cycling test when compared with cycling alone over a training time of this length. It is possible that with this population, various factors such as acute fatigue, strength, and aerobic gains from the cycling training, in addition to well-developed bases of strength and conditioning from previous training, reduced differences between groups in both strength gains and cycling performance.     

1-Set vs. 3-set resistance training: a crossover study

This crossover study was conducted to investigate the effects of a 1-set and 3-set strength training program. The subjects were untrained men and women who were randomly signed into 1 of 3 groups: 10 subjects trained during the first 9 weeks (training period 1) with 1 set and 8-12 repetitions per set. After the break (9 weeks), they trained with 3 sets and 8-12 repetitions in training period 2. Twelve subjects started with the 3-set program and continued with the 1-set regime after the break. The control group (n = 7) did not train. The subjects were tested on 1 repetition maximum (1RM) for the biceps curl, leg press (unilateral: left and right), and bench press. Analysis of the data was done in a sampled manner for each strength training program (1-set and 3-set). The 1-set (n = 22) and 3-set (n = 22) programs led to significantly (p < 0.05) improved 1RM performances in every exercise. The relative improvements (%) for the 1RM were significantly higher during the 3-set program for the biceps curl and the bench press compared with the 1-set program. The control group exhibited no changes in any of the tested parameters over the course of this study. The design of this study allowed insight into the effects of different strength training volume without any genetical variations. The same subjects improved their 1RM during the 3-set program by 2.3 kg (biceps curl; corresponding effect size = 0.24), 8.9 kg (leg press right; 0.30), 10.9 kg (leg press left; 0.28), and 2.5 kg (bench press; 0.09) more than during the 1-set program. Depending on the goals of each trainee, these differences between the effects of different strength training volumes indicate that it may be worth spending more time on working out with a 3-set strength training regime.     

Landscape-moderated biodiversity effects of agri-environmental management: a meta-analysis

Agri-environmental management (AEM) is heralded as being key to biodiversity conservation on farmland, yet results of these schemes have been mixed, making their general utility questionable. We test with meta-analysis whether the benefits of AEM for species richness and abundance of plants and animals are determined by the surrounding landscape context. Across all studies (109 observations for species richness and 114 observations for abundance), AEM significantly increased species richness and their abundance. More specifically, we test the hypothesis that AEM benefits species richness and abundance (i.e. increases the difference between fields with and without AEM) more in simple than in complex landscapes. In croplands, species richness but not abundance was significantly enhanced in simple but not in complex landscapes. In grasslands, AEM effectively enhanced species richness and abundance regardless of landscape context. Pollinators were significantly enhanced by AEM in simple but not in complex landscapes in both croplands and grasslands. Our results highlight that the one-size-fits-all approach of many agri-environmental programmes is not an efficient way of spending the limited funds available for biodiversity conservation on farmland. Therefore, we conclude that AEM should be adapted to landscape structure and the species groups at which they are targeted.     

Comparison of resistance and conduit vessel nitric oxide-mediated vascular function in vivo: effects of exercise training.

Exercise training improves vascular function in subjects with cardiovascular disease and risk factors, but there is mounting evidence these vascular adaptations may be vessel bed specific. We have therefore examined the hypothesis that exercise-induced improvements in conduit vessel function are related to changes in resistance vessel function. Endothelium-dependent and -independent conduit vessel function were assessed by using wall-tracking of high-resolution brachial artery ultrasound images of the response to flow-mediated dilation (FMD) and nitroglycerine [glyceryl trinitrate (GTN)] administration. Resistance vessel endothelium-dependent and -independent function were assessed using intrabrachial administration of acetylcholine (ACh) and nitroprusside (SNP). Randomized crossover studies of 8-wk exercise training were undertaken in untreated hypercholesterolemic (n = 10), treated hypercholesterolemic (n = 10), coronary artery disease (n = 8), and Type 2 diabetic subjects (n = 15). Exercise training significantly enhanced responses to ACh (P < 0.05) and FMD (P < 0.0001). There were no significant changes in either SNP or GTN responses. The correlation between ACh and FMD responses at entry was not significant (r = 0.186; P = 0.231), and training-induced changes in the ACh did not correlate with those in FMD (r = -0.022; P = 0.890). Similarly, no correlation was evident between the SNP and GTN responses at entry (r = -0.010; P = 0.951) or between changes in these variables with training (r = -0.211; P = 0.191). We conclude that, although short-term exercise training improves endothelium-dependent nitric oxide-mediated vascular function in both conduit and resistance vessels, the magnitude of these improvements are unrelated.     

Combined aerobic and resistance training and vascular function: effect of aerobic exercise before and after resistance training.

Aerobic exercise training combined with resistance training (RT) might prevent the deterioration of vascular function. However, how aerobic exercise performed before or after a bout of RT affects vascular function is unknown. The present study investigates the effect of aerobic exercise before and after RT on vascular function. Thirty-three young, healthy subjects were randomly assigned to groups that ran before RT (BRT: 4 male, 7 female), ran after RT (ART: 4 male, 7 female), or remained sedentary (SED: 3 male, 8 female). The BRT and ART groups performed RT at 80% of one repetition maximum and ran at 60% of the targeted heart rate twice each week for 8 wk. Both brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD) after combined training in the BRT group did not change from baseline. In contrast, baPWV after combined training in the ART group reduced from baseline (from 1,025 +/- 43 to 910 +/- 33 cm/s, P < 0.01). Moreover, brachial artery FMD after combined training in the ART group increased from baseline (from 7.3 +/- 0.8 to 9.6 +/- 0.8%, P < 0.01). Brachial artery diameter, mean blood velocity, and blood flow in the BRT and ART groups after combined training increased from baseline (P < 0.05, P < 0.01, and P < 0.001, respectively). These values returned to the baseline during the detraining period. These values did not change in the SED group. These results suggest that although vascular function is not improved by aerobic exercise before RT, performing aerobic exercise thereafter can prevent the deteriorating of vascular function.     

Training with unilateral resistance exercise increases contralateral strength.

Evidence that unilateral training increases contralateral strength is inconsistent, possibly because existing studies have design limitations such as lack of control groups, lack of randomization, and insufficient statistical power. This study sought to determine whether unilateral resistance training increases contralateral strength. Subjects (n = 115) were randomly assigned to a control group or one of the following four training groups that performed supervised elbow flexion contractions: 1) one set at high speed, 2) one set at low speed, 3) three sets at high speed, or 4) three sets at low speed. Training was 3 times/wk for 6 wk with a six- to eight-repetition maximum load. Control subjects attended sessions but did not exercise. Elbow flexor strength was measured with a one-repetition maximum arm curl before and after training. Training with one set at slow speed did not produce an increase in contralateral strength (mean effect of -1% or -0.07 kg; 95% confidence interval: -0.42-0.28 kg; P = 0.68). However, three sets increased strength of the untrained arm by a mean of 7% of initial strength (additional mean effect of 0.41 kg; 95% confidence interval: 0.06-0.75 kg; P = 0.022). There was a tendency for training with fast contractions to produce a greater increase in contralateral strength than slow training (additional mean effect of 5% or 0.31 kg; 95% confidence interval: -0.03-0.66 kg; P = 0.08), but there was no interaction between the number of sets and training speed. We conclude that three sets of unilateral resistance exercise produce small contralateral increases in strength.