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PubMed1997

Effects of maximal effort strength training with different loads on dynamic strength, cross-sectional area, load-power and load-velocity relationships.

The effects of maximal effort strength training with different loads on maximal strength, muscle cross-sectional area, the load-power and load-velocity relationship were investigated in the elbow flexors. Physical education students were matched into three groups; G90 (n = 9) trained with a load of 90%. G35 (n = 11) with 35%, and G15 (n = 10) with 15% of IRM (1 repetition maximum). Training consisted of three to five sets, performed three times a week for 9 weeks. Each set consisted of two, seven and ten repetitions in G90. G35 and G15, respectively. Training was performed with the nondominant arm, and the dominant arm served as control. The IRM increased 15.2 (SD 4.5)% (P < 0.001) in G90, 10.1 (SD 5.9)% (P < 0.001) in G35 and 6.6 (SD 7.9)% (P < 0.05) in G15. The increase in G90 was significantly larger than for G15 (P < 0.05). In the untrained arm, IRM also increased for G90 and G15. In contrast to G90. G15 showed a similar increase in IRM in both arms. Cross-sectional area of the elbow, flexors did not change for G90 and G15. while G35 increased 2.8% (P < 0.05). Maximal power and velocity were tested at 2.5 kg and at 15%, 25%, 35%, 50%, 70% and 90% of pretraining IRM. Power increased for all tested loads in G90 and G35, and G15 showed an increase in power at 15%, 25% and 50% of IRM. No significant differences in increase in power could be found among the three groups at loads equal to or less than 50%, but at 70% and 90% of IRM the increase was larger for G90 and G35 than for G15 (P < 0.05). The G35 showed a similar increase in power at all loads tested whereas G90 showed load specificity in the effect of the training. There was a correlation between IRM and maximal power (r = 0.93, P < 0.0001), and between IRM and power at load 2.5 kg (r = 0.73, P < 0.0001). In conclusion, training with loads of 15% and 35% of IRM resulted in an increase in IRM. Although the increase in maximal power after training at 90% of IRM showed some load specificity. It also increased maximal power at 15% of IRM. Training at loads near maximal power output would seem to increase power efficiently over a wide load range. The high correlation between IRM and maximal power at load 2.5 kg also would indicate that maximal strength is important for performance at light loads.

Adult↗

PubMed2006

Respiratory muscle strength training: functional outcomes versus plasticity.

Respiratory muscle strength training is a paradigm that has been used for numerous years with a variety of populations including but not limited to spinal cord injury, chronic obstructive pulmonary disease, multiple sclerosis, Parkinson's disease, voice disordered, sedentary elderly, and healthy young. The respiratory muscle strength program discussed here is an expiratory muscle strength training and uses a pressure threshold device with a regimented treatment protocol. The primary purpose of the expiratory muscle strength training program is to promote strength in the expiratory muscles. The training protocol occurs five times per day, 5 days a week, and consists of ~15-20 minutes per day of training by the user at home. The device threshold is changed weekly by a clinician to maintain a threshold load of 75% of an individual's maximum expiratory pressure. The threshold setting of the device is always based on the individual's recorded maximum expiratory pressure generated into a digital pressure gauge. Results of 4 weeks of expiratory muscle strength training protocols indicate up to a 50% improvement for healthy subjects, those with multiple sclerosis, and those with spinal cord injury. The potential transfer of expiratory muscle strength to functional outcomes is discussed, as well as how strength-training paradigms may influence cortical plasticity.

Breathing Exercises↗

PubMed1986

The effects of hydraulic resistance strength training in pre-pubertal males.

In order to examine the effectiveness and safety of hydraulic resistance strength training in young males, 26 pre-pubertal males (mean age = 8.2 +/- 1.3 yr) completed a 14-wk strength training study. Subjects were evaluated before and after the 14-wk experimental period for pubertal state (Tanner's sexual maturity rating, serum testosterone, and serum dihydroepiandrosterone sulfate). Effectiveness of the strength training program was determined by measuring pre-post differences in: isokinetic strength for flexion and extension at the knee and elbow joints at two speeds (30 degrees and 90 degrees X s-1) (KIN COM, Chattecx, Inc., Chattanooga, TN), flexibility, standing long jump, vertical jump, body composition parameters, maximal oxygen consumption, and creatinine phosphokinase. Safety of strength training was assessed by biphasic musculoskeletal scintigraphy before and after the program and by physician evaluation of complaints by subjects. Strength training subjects (N = 16) participated in a 45 min/session, 3 session/wk, 14-wk supervised strength training program with an attendance rate of 91.5%. Participants performed concentric work using hydraulic resistance equipment (Hydra-Fitness Industries, Belton, TX). Eccentric work was not performed. Control subjects (N = 10) did not strength train but did participate in sport activities and activities of daily living. Results indicated that strength training subjects increased isokinetic strength as a result of strength training (average concentric work/repetition increases by 18.5 to 36.6% for the eight motions tested; torque scores over the first 90% of the range of motion increases by 13.1 to 45.1% for the eight motions tested). These changes were significantly greater than changes seen in the control group (P less than 0.05). Strength training subjects also demonstrated significant improvements (as compared to control subjects) in vertical jump (+10.4%), flexibility (+8.4%), and maximal oxygen consumption [+19.4% (l X min-1), +13.8% (ml X kg X min-1)] after the experimental period. Musculoskeletal scintigraphy revealed no evidence of damage to epiphyses, bone, or muscle as a result of strength training. Only one strength training-related injury was reported (left shoulder pain, 3 strength training sessions missed). In contrast, six strength training subjects sustained injuries during activities of daily living, resulting in 47 missed strength training sessions. It was concluded that, in the short term, supervised concentric strength training using hydraulic resistance equipment is safe and effective in pre-pubertal boys.

Anthropometry↗

PubMed2004

Strength training among adults aged >/=65 years--United States, 2001.

Strength training (also referred to as resistance training) enables adults to improve their overall health and fitness by increasing muscular strength, endurance, and bone density and by improving their insulin sensitivity and glucose metabolism. For older adults (i.e., persons aged >/=65 years), strength-training exercises are recommended to decrease the risk for falls and fractures and to promote independent living. The American College of Sports Medicine recommends that adults include strength training as part of a comprehensive physical activity program. A national health objective for 2010 is to increase to 30% the proportion of adults who perform, >/=2 days per week, physical activities that enhance and maintain muscular strength and endurance. To determine the percentage and characteristics of older adults who perform strength training consistent with this objective, CDC analyzed data from the 2001 National Health Interview Survey (NHIS). This report summarizes the results of that analysis, which indicated that approximately 12% of persons aged 65-74 years and 10% of persons aged >/=75 years met the strength-training objective. These findings underscore the need for programs that encourage older adults to incorporate strength training into their lives along with regular physical activity.

Aged↗

PubMedDate not supplied

Muscle hypertrophy, strength development, and serum hormones during strength training in elderly women with fibromyalgia.

OBJECTIVE: To examine the effects of strength training on maximal force, cross-sectional area (CSA), and electromyographic (EMG) activity of muscles and serum hormone concentrations in elderly females with fibromyalgia (FM). METHODS: Twenty-six patients with FM were randomly assigned to a training (FMT; n = 13; mean age 60 years) or a control (FMC; n = 13; 59 years) group. FMT performed progressive strength training twice a week for 21 weeks. The measurements included maximal isometric and concentric leg extension forces, EMG activity of the vastus lateralis and medialis, CSA of the quadriceps femoris, and serum concentrations of testosterone (T), free testosterone (FT), growth hormone (GH), insulin-like growth factor-1 (IGF-1), dehydroepiandrosterone sulfate (DHEAS), and cortisol. Subjectively perceived symptoms of FM were also assessed. RESULTS: All patients were able to complete the training. In FMT strength training led to increases of 36% (p<0.001) and 33% (p<0.001) in maximal isometric and concentric forces, respectively. The CSA increased by 5% (p<0.001) and the EMG activity in isometric action by 47% (p<0.001) and in concentric action by 57% (p<0.001). Basal serum hormone concentrations remained unaltered during strength training. The subjective perceived symptoms showed a minor decreasing tendency (ns). No statistically significant changes occurred in any of these parameters in FMC. CONCLUSION: Progressive strength training increases strength, CSA, and voluntary activation of the trained muscles in elderly women with FM, while the measured basal serum hormone concentrations remain unaltered. Strength training benefits the overall physical fitness of the patients without adverse effects or any exacerbation of symptoms and should be included in the rehabilitation programmes of elderly patients with FM.

Aged↗

PubMed1994

Superiority of treadmill walking exercise versus strength training for patients with peripheral arterial disease. Implications for the mechanism of the training response.

BACKGROUND: In patients with intermittent claudication, a supervised walking exercise program increases peak exercise performance and community-based functional status. Patients with peripheral arterial disease also have muscle weakness in the affected extremity that may contribute to the walking impairment. However, the potential benefits of training modalities other than walking exercise, such as strength training, have not been critically evaluated in this patient population. The present study tested the hypothesis that a strength training program would be as effective as treadmill walking exercise and that combinations of strengthening and walking exercise would be more effective than either alone in improving exercise performance. METHODS AND RESULTS: Twenty-nine patients with disabling claudication were randomized to 12 weeks of supervised walking exercise on a treadmill (3 h/wk at a work intensity sufficient to produce claudication), strength training (3 h/wk of resistive training of five muscle groups of each leg), or a nonexercising control group. Graded treadmill testing was performed to maximally tolerated claudication pain to define changes in peak exercise performance. After 12 weeks, patients in the treadmill training program had a 74 +/- 58% increase in peak walking time as well as improvements in peak oxygen consumption (VO2) and the onset of claudication pain. Patients in the strength-trained group had a 36 +/- 48% increase in peak walking time but no change in peak VO2 or claudication onset time. Control subjects had no changes in any of these measures over the 12-week period. After the first 12 weeks, patients in the initial walking exercise group continued for 12 more weeks of supervised treadmill training. This resulted in an additional 49 +/- 53% increase in peak walking time (total of 128 +/- 99% increase over the 24 weeks). After the initial 12 weeks, patients in the strength-trained group began 12 weeks of supervised treadmill training, and patients in the control group participated in a 12-week combined program of strengthening and treadmill walking exercise. The combined strength and treadmill training program and treadmill training after 12 weeks of strength training resulted in increases in peak exercise performance similar to those observed with 12 weeks of treadmill training alone. CONCLUSIONS: A supervised treadmill walking exercise program is an effective means to improve exercise performance in patients with intermittent claudication, with continued improvement over 24 weeks of training. In contrast, 12 weeks of strength training was less effective than 12 weeks of supervised treadmill walking exercise. Finally, strength training, whether sequential or concomitant, did not augment the response to a walking exercise program.

Aged↗

PubMed1990

Strength training in the rehabilitation of cruciate ligament tears.

Pure strength training will result in good functional results in most patients with anterior or posterior cruciate ligament injuries. In a randomised study it was shown that functional training without specific strength training will result in at least comparable results to isokinetic training. In order to increase compliance and to improve the results of training a new rehabilitation programme combines pure strength training and functional training. The aim of this treatment is to restore the dynamic stability of the knee.

Exercise Therapy↗

PubMed1983

Alterations of mechanical characteristics of human skeletal muscle during strength training.

To investigate the influence of strength training on the mechanical characteristics of human skeletal muscle, 14 male subjects went through training of combined heavy concentric and eccentric contractions three times a week for 16 weeks. The strength training program consisted mainly of dynamic exercises for leg extensors with loads of 80 to 120% of one maximum repetition. The force-time curves produced during various vertical jumps were the basis for calculation of various mechanical parameters. In addition to a great increase (p less than 0.001) in maximal isometric force, heavy resistance strength training also caused significant (p less than 0.05-0.01) increases in heights and in various mechanical parameters in positive work phases of vertical and drop jumps. The increase in positive force during a fast dynamic contraction was correlated (p less than 0.01) with the reduced time to produce a certain submaximal force level in isometric condition. No changes in the elastic properties of the muscle were observed as judged from the difference between the counter-movement and squat jumps. When the training was followed by the 8-week detraining period a great decrease (p less than 0.001) in maximal force took place, but only minor changes (ns) were observed in fast force production.

Adult↗

PubMed1997

Older adults' experiences of a strength training program.

Despite the recognized benefits of strength training in preventing physical and functional decline among older adults, little information exists on their views of this exercise modality. This study used focus groups to obtain an in-depth understanding of older adults' attitudes and concerns about a strength training intervention and to identify factors that determined their adherence to this exercise program. Three focus groups were conducted with 24 former participants after the completion of the 16-week intervention. Major themes that emerged from the focus group discussions were categorized according to Dishman, Sallis, and Orenstein's [1] framework of factors influencing adherence, including personal, activity, and environmental characteristics. The most frequently reported factors were enjoyment of strength training, accessibility of the exercise facility, and the social reinforcement provided by exercise leaders and partners. Recommendations for strength training program development with older adults are discussed in light of these factors.

Aged↗

PubMed2005

Strength training: what the team physician needs to know.

Strength training has become an integral part of preparing for and participating in sports. Strength is one of the four components of athleticism, along with power, speed, and agility. Optimal strength training and conditioning workouts are best directed by a coach with formal training in this discipline. Unfortunately, many high school and some college programs do not have access to certified strength and conditioning coaches. This task often falls to the individual sport coaches and medical staff (athletic trainers and physicians). In this article we present a framework for practical strength training knowledge including the concepts of specificity, prioritization, periodization, and progressive overload. We also discuss concepts of the sports medicine team and its approach to training and conditioning. This framework will give physicians and other athletic heath care providers the basic information needed to design and implement a safe and effective strength training program.

Adolescent↗

PubMed2006

Comparison of once-weekly and twice-weekly strength training in older adults.

BACKGROUND: Strength training has been shown to benefit the health and function of older adults. OBJECTIVE: To investigate whether one set of exercises performed once a week was as effective in increasing muscle strength as training twice a week. METHODS: 18 subjects (7 women and 11 men) aged 65-79 years were randomly assigned to two groups. Both groups performed one set of exercises to muscular fatigue; group 1 trained 1 day/week and group 2 trained 2 days/week on three lower and three upper body exercises for 9 weeks. The data were analysed using a mixed model 2 x 2 analysis of variance. RESULTS: A significant main effect of time (p<0.001), but not group, on one-repetition maximum scores was observed. No significant interaction was observed between time and group and therefore no difference in strength changes between training once a week versus twice a week after 9 weeks. CONCLUSIONS: One set of exercises performed once weekly to muscle fatigue improved strength as well as twice a week in the older adult. Our results provide information that will assist in designing strength-training programmes that are more time and cost efficient in producing health and fitness benefits for older adults.

Aged↗

PubMed1988

Serum thyroid hormones, thyrotropin and thyroxine binding globulin during prolonged strength training.

The effects of progressive strength training for 24 weeks on maximal strength and pituitary-thyroid function were studied in 21 males during the training and during the following detraining period of 12 weeks. Maximal strength increased greatly (p less than 0.001) in the first 20 weeks, followed by a plateau phase in the last 4 weeks of training. Maximal strength decreased greatly (p less than 0.001) during the detraining period. The concentrations of serum total (T4) and free thyroxine (fT4) decreased (p less than 0.05 and less than 0.01, respectively) during the training period and they rose to pretraining levels during the detraining period. During the most intense training phase (the last 4 weeks) there was a positive correlation between the changes in serum fT4 concentrations and the changes in maximal force (r = 0.56; p less than 0.01). No statistically significant changes occurred in the levels of serum triiodothyronine, thyrotropin or thyroxine binding globulin. The results show that prolonged intensified strength training can slightly decrease the concentrations of serum total and free T4. These small changes cannot have any clinical significance, and even their physiological significance may be only marginal.

Adult↗

PubMedDate not supplied

Effect of strenuous strength training on the Na-K pump concentration in skeletal muscle of well-trained men.

This study examined how strenuous strength training affected the Na-K pump concentration in the knee extensor muscle of well-trained men and whether leg muscle strength and endurance was related to the pump concentration. First, the pump concentration, taken as 3H-ouabain binding, was measured in top alpine skiers since strength training is important to them. Second, well-trained subjects carried out strenuous eccentric resistance training either 1, 2, or 3 times.week-1 for 3 months. The Na-K pump concentration, the maximal muscle strength in a full squat lift (one repetition maximum, 1 RM), and the muscle endurance, taken as the number of full squat lifts of a mass of 70% of the 1 RM load, were measured before and after the training period. The mean pump concentration of the alpine skiers was 425 (SEM 11) nmol.kg-1 wet muscle mass. The subjects in part two increased their maximal strength in a dose-dependent manner. The muscle endurance increased for all subjects but independently of the training programme. From a mean starting value of 356 (SEM 6) nmol.kg-1 the mean Na-K pump concentration increased by 54 (SEM 15) nmol.kg-1 (+15%, P < 0.001) when the results for all subjects were pooled. The effect was larger for those who had trained twice a week than for those who had trained only once a week (P = 0.025), suggesting that the effect of strength training depended on the amount of training carried out. The muscle strength and endurance were not related to the pump concentration, suggesting that the pumping power of this enzyme did not limit the performance during heavy lifting. However, the individual improvements in the endurance test during the training period correlated with the individual changes in the pump concentration (rSpearman = 0.5; P = 0.01) which could mean that a common factor both increases the pump concentration and makes the muscles more adapted to repeated heavy lifting.

Adult↗

PubMedDate not supplied

Developing a strength training program for older adults: planning, programming, and potential outcomes.

Muscle strength is important to older adults in maintaining an independent lifestyle and completing activities of daily living. In this article, the authors discuss changes in muscular functioning that commonly accompany the disuse associated with aging, as well as the impact that strength training can have on the older adult's muscle functioning. The article presents the essential components of developing a strength training program: pretesting, setting individualized goals, designing a strength training program, and establishing methods to evaluate the participants' progress. It also lists the benefits of strengthening particular muscle groups. Strength training programs for older adults should be developed on the basis of individualized expectations and goals, with the ultimate goal of facilitating the older individual's lifestyle and independence. Older adults who have participated in a strength training program have reported the following benefits of participation: improved body image, greater flexibility, increased strength, and increased self-confidence.

Age Factors↗

PubMed2002

Comparison of 1 and 2 days per week of strength training in children.

The purpose of this study was to compare the effects of 1 and 2 days per week of strength training on upper body strength, lower body strength, and motor performance ability in children. Twenty-one girls and 34 boys between the ages of 7.1 and 12.3 years volunteered to participate in this study. Participants strength trained either once per week (n = 22) or twice per week (n = 20) for 8 weeks at a community-based youth fitness center. Each training session consisted of a single set of 10-15 repetitions on 12 exercises using child-size weight machines. Thirteen children who did not strength train served as age-matched controls. One repetition maximum (1RM) strength on the chest press and leg press, handgrip strength, long jump, vertical jump, and flexibility were assessed at baseline and posttraining. Only participants who strength trained twice per week made significantly greater gains in 1RM chest press strength, compared to the control group (11.5 and 4.4% respectively, p < .05). Participants who trained once and twice per week made gains in 1RM leg press strength (14.2 and 24.7%, respectively) that were significantly greater than control group gains (2.4%). On average, participants who strength trained once per week achieved 67% of the 1RM strength gains. No significant differences between groups were observed on other outcome measures. These findings support the concept that muscular strength can be improved during the childhood years and favor a training frequency of twice per week for children participating in an introductory strength training program.

Adaptation, Physiological↗

PubMed2004

Outcomes of progressive resistance strength training following stroke: a systematic review.

OBJECTIVE: To determine whether progressive resistance strength training reduces impairments, activity limitations and participation restrictions after stroke. METHODS: Electronic databases were searched to find trials conducted from 1966 to 2002. Articles were assessed independently by two reviewers according to the following inclusion criteria: (1) population: adults with stroke, (2) intervention: progressive resistive strength training in isolation, and (3) outcomes: changes in body function, physical activity or societal participation. RESULTS: From the 350 articles initially identified, eight met the criteria for detailed review. Three were randomized controlled trials, with the remainder being single-case time-series analyses or pre-post trials. The five trials that measured impairments of muscle strength showed positive outcomes for progressive resistance strength training, with large effect sizes (d = 1.2-4.5). Few negative effects of strength training were reported, and these were minor. Only three of the eight trials that measured activity limitations reported improvements in activities such as walking and stair climbing. The effects of strength training on societal participation could not be determined due to insufficient data. CONCLUSIONS: There is preliminary evidence that progressive resistance strength training programmes reduce musculoskeletal impairment after stroke. Whether strengthening enhances the performance of functional activities or participation in societal roles remains unknown.

Clinical Trials as Topic↗

PubMed1997

A follow-up study on the effects of strength training with older adults.

This study was designed to evaluate changes in strength, and functional ability in older adults after completion of a 4-month strength training intervention. The follow-up sample consisted of 30 older adults (12 men and 18 women, 100% Caucasian; mean age = 71.8) who were evaluated an average of 15 months after completion of the training intervention. At the follow-up testing, 45% of the subjects reported that they continued strength training on their own after the conclusion of the strength training intervention. The data were evaluated for pre-, post-training, and follow-up differences via repeated measures ANOVA and Scheffé HSD tests. After the intervention, the subjects showed significant improvement in muscular strength and one of the functional tasks measuring coordination. From post- to the 15 month follow-up, the subjects declined in muscular strength and functional ability (mobility). However, at follow-up the subjects were stronger and had better coordination than before they entered the strength training intervention. These results suggest benefits were retained 15 months after the strength training intervention in a sample of relatively healthy older adults.

Aged↗

PubMed1989

Muscle fiber-specific glycogen utilization in strength-trained males and females.

This study evaluated the effect of strength training on glycogen utilization in slow twitch (ST) and fast twitch (FT) muscle fibers during repeated maximal unilateral isokinetic leg extensions at 180 degrees.s-1. Strength-trained (5 males, 4 females) and untrained (4 males, 6 females) subjects performed three sets of 50 maximum voluntary contractions (MVC) at this velocity with 10-min rest intervals between sets. Biopsies were taken from the vastus lateralis muscle before and after each exercise session. Glycogen content of the fibers was quantified as optical density (OD) using microspectrophotometric densitometry on serial cross-sections of muscle tissue stained with a periodic acid Schiff reagent stain after individual fibers were identified as ST or FT according to a stain for myofibrillar ATPase activity. Analysis of variance with repeated measures yielded the following results: OD, i.e., glycogen, was reduced similarly in both fiber types after exercise, but only in the males (P = 0.02); there was no significant main effect of training status per se (i.e., strength-trained vs untrained). These results indicate that years of strength training do not change the pattern of muscle fiber-specific glycogen utilization during repeated dynamic MVCs.

Adult↗