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Results for “Resistance Training”

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At least 91 records · Page 5Linked to original sources

PubMed2026

Comparative effects of 12-week resistance training on unstable and stable surfaces on muscle stiffness, muscle co-activation, and balance in older patients with knee osteoarthritis.

OBJECTIVE: This randomized trial compared the effects of unstable resistance training (URT), involving resistance exercises on unstable surfaces, and stable resistance training (SRT), performed on stable surfaces, on muscle stiffness, co-activation, and balance in older adults with knee osteoarthritis (KOA). We hypothesized that URT would yield greater improvements by enhancing neuromuscular adaptability. METHODS: Fifty patients with KOA were randomly assigned to the URT group (n = 25) or the SRT group (n = 25). After attrition, 46 participants (URT: n = 23; SRT: n = 23) completed the intervention and were included in the final analysis. Both groups completed a 12-week supervised lower-limb resistance training program (3 sessions/week) consisting of 10 exercises performed under either unstable or stable support conditions. RESULTS: After 12 weeks of intervention, both groups showed significant reductions in pain intensity (p < 0.001). However, compared with the SRT group, the URT group demonstrated significantly greater reductions in quadriceps stiffness (p < 0.05), selected hamstring stiffness outcomes (p < 0.05), and quadriceps-hamstring co-activation (p < 0.001), alongside superior improvements in both dynamic balance and static balance (all p < 0.05). CONCLUSION: While both training modalities are effective for pain relief, URT elicited greater improvements in balance-related performance and neuromuscular-mechanical outcomes than SRT in older adults with KOA. These findings suggest that incorporating unstable support conditions into resistance training may provide additional rehabilitation benefits for this population.

Humans↗

PubMedDate not supplied

Resistance training alters cytokine gene expression in skeletal muscle of adults with type 2 diabetes.

Resistance training results in muscle hypertrophy and improves glycemic control in patients with type 2 diabetes. Whether resistance training modulates inflammation in muscles of diabetic patients remains unknown. We examined the expression of genes encoding the cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) as well as the pan-leukocyte marker CD18. Thirty men and women (67+/-7 years) were randomized to either 16 weeks of resistance training and usual diabetes care (EX) or to usual diabetes care only (CON). Muscle biopsies were obtained from the vastus lateralis muscle prior to the 16-week intervention, and 72 h following the maximal strength test post-intervention. Fiber cross-sectional area (CSA) was determined following ATPase staining. Cytokine and CD18 transcript levels were assessed by real-time PCR. Resistance training increased CSA of type I and II fibers (both P <0.05) and IL-1beta transcript levels (P = 0.05). TNF-alpha (P<0.05) and TGF-beta1 transcripts (P<0.05) increased over time in the EX group, but these increases did not differ from those in the CON group. In both groups, the increase in CD18 transcripts remained minimal. The two groups differ by the relationship between changes in CD18 and changes in cytokine transcripts, suggesting that resistance training affects the source of cytokines in muscle. Our studies establish that resistance training in older adults with type 2 diabetes results in muscle fiber hypertrophy, despite a greater accumulation of inflammatory cytokine transcripts in muscle.

Aged↗

PubMed2006

The effects of systematic resistance training in the elderly.

The aim of the study was to examine the effects of a maximal resistance training following the principles of the most effective resistance training known from sport adapted to elderly people. Twenty-four subjects were randomly assigned into a training group (10 females and 4 males, age; 76.2 +/- 3.2 years) that underwent a training program and a control group (6 females and 4 males, age; 76.6 +/- 2.7 years) that did not participate in the training program. Before and after the training period, both groups were identically examined (blood and urine sample, spiroergometric testing, morphological measurements). The training group underwent a 12-week training program. Eight different exercises for the largest muscle groups of the largest joints were defined as one training circle. Training took place twice a week and commenced with two training circles per week (one circle per training session). After every four weeks, one training circle per week was added until four training circles per week were reached. Before, after every four weeks (changes in training amount) and after the training period, the maximum strength was measured. Data was analysed by the independent T-test and the analysis of variance, in case of significance, the dependent T-test and the Scheffé-test were used. In the resistance training group, the fat-free body mass was increased by approximately 2.9 +/- 0.5 kg, with no significant difference between females and males. Ergometrical fitness was increased by approximately 15 %, while the maximum oxygen uptake was increased by approximately 12 %. Maximum strength was increased between 26 % (bench pull) and 38 % (leg press). Resistance training that consisted of two training sessions per week was found to be at least as efficient as resistance training that included three training sessions per week, provided that the number of sets performed were equal. Seventy-five-year-old females were found to have a significantly higher body fat content than males of the same age (37 % versus 26 %, respectively). However, the decrease in body fat mass due to resistance training was found to be equal in both females and males (- 4 +/- 0.8 kg). Furthermore, there was almost no difference in muscle strength between the sexes for this age group (for example; leg press: females 86 kg versus males 82 kg).

Adipose Tissue↗

PubMed1990

Effects of eccentric and concentric muscle actions in resistance training.

The adaptive responses to two different resistance training regimens were compared. Healthy males performed five sets of either 12 maximum bilateral concentric (Grp CON; n = 11) or six pairs of maximum bilateral eccentric and concentric (Grp ECCON; n = 11) quadriceps muscle actions three times per week for 12 weeks. Uni- and bilateral eccentric and concentric peak torque at various angular velocities, vertical jump height and three-repetition maximum half-squat were measured before and after training. Muscle biopsies were obtained from m. vastus lateralis and analysed for fibre type composition and area using histochemical techniques. In contrast to a control group (n = 7), performing no training, Grps CON and ECCON demonstrated marked increases (P less than 0.05) in overall eccentric (19 and 37% respectively) and concentric (15 and 26% respectively) peak torques. Grp ECCON, however, showed greater (P less than 0.05) increases in peak torque, vertical jump height and three repetition maximum than Grp CON. The 7% increases in slow-twitch fibre area in Grps CON and ECCON and in fast-twitch fibre area in Grp CON were non-significant. This study suggests that increases in peak torque and strength-related performance parameters were greater following a programme consisting of maximum concentric and eccentric muscle actions than resistance training using concentric muscle actions only. Because increases in muscle fibre areas were small it is also suggested that the increased muscle strength shown subsequent to short-term accommodated resistance training is mainly due to neural adaptation.

Adaptation, Physiological↗

PubMed2006

Resistance training and detraining effects on flexibility performance in the elderly are intensity-dependent.

The present investigation attempted to determine whether resistance exercise intensity affects flexibility and strength performance in the elderly following a 6-month resistance training and detraining period. Fifty-eight healthy, inactive older men (65- 78 yrs) were randomly assigned to 1 of 4 groups: a control group (C, n = 10), a low-intensity resistance training group (LI, n = 14, 40% of 1 repetition maximum [1RM]), a moderate-intensity resistance training group (MI, n = 12, 60% of 1RM), or a high-intensity resistance training group (HI, n = 14, 80% of 1RM). Subjects in exercise groups followed a 3 days per week, whole-body (10 exercises, 3 sets per exercise) protocol for 24 weeks. Training was immediately followed by a 24-week detraining period. Strength (bench and leg press 1RM) and range of motion in trunk, elbow, knee, shoulder, and hip joints were measured at baseline and during training and detraining. Resistance training increased upper- (34% in LI, 48% in MI, and 75% in HI) and lower-body strength (38% in LI, 53% in MI, and 63% in HI) in an intensity-dependent manner. Flexibility demonstrated an intensity-dependent enhancement (3-12% in LI, 6-22% in MI, and 8-28% in HI). Detraining caused significant losses in strength (70-98% in LI, 44-50% in MI, and 27-29% in HI) and flexibility (90-110% in LI, 30-71% in MI, and 23-51% in HI) in an intensity-dependent manner. Results indicate that resistance training by itself improves flexibility in the aged. However, intensities greater than 60% of 1RM are more effective in producing flexibility gains, and strength improvement with resistance training is also intensity-dependent. Detraining seems to reverse training strength and flexibility gains in the elderly in an intensity-dependent manner.

Adaptation, Physiological↗

PubMed1989

Weaning from mechanical ventilation: adjunctive use of inspiratory muscle resistive training.

We used inspiratory resistive training (IRT) in an effort to improve the respiratory muscle endurance of 27 patients with respiratory failure who had failed repeated weaning attempts using standard techniques. Seven patients had primary neuromuscular diseases; the other 20 had primary lung diseases. All patients had stable respiratory failure, without gross malnutrition or electrolyte disorders. Their best initial T-piece duration averaged 6.4 +/- 8.4 (SD) h, with pHa 7.33 +/- 0.09 and PCO2 63 +/- 4 torr at the end of the T-piece trial. We provided a mean of five weekly training sessions of spontaneous breathing through an adjustable nonlinear resistor, with gradually increasing duration and resistance. When initial T-piece tolerance was less than 2 h, two to ten breaths of mechanical ventilation were provided during IRT sessions. No training session exceeded 30 min, and mechanical ventilation was provided between IRT sessions. Under this regimen, maximal inspiratory pressure improved from -37 +/- 15 to -46 +/- 15 cm H2O (p less than .001) and vital capacity improved from 561 +/- 325 to 901 +/- 480 ml (p less than .001). Twelve of the 27 patients were successfully weaned after 10 to 46 days; five more were weaned to nocturnal ventilation, for a total of 63%. We conclude that IRT can improve respiratory muscle strength and endurance in patients with respiratory failure, and can allow many of them to be weaned from mechanical ventilation.

Aged↗

PubMed2000

Effects of long term resistance training on left ventricular morphology.

OBJECTIVES: To assess the effects of long term (mean +/- SD 10+/-5 years, range three to 25 years) resistance training on left ventricular (LV) dimensions and mass. METHODS AND RESULTS: The study participants were 21 elite male power-lifters (age 33.4+/-5.9 years) and 10 sedentary male control subjects (age 30.9+/-4.2 years). Two-dimensionally guided transthoracic M-mode echocardiograms were obtained at rest to quantify LV diastolic cavity dimension, posterior wall thickness, ventricular septal wall thickness and LV mass. Long term resistance training was not associated with an alteration in LV diastolic cavity dimension (resistance trained 54. 4+/-4.3 mm versus control 51.8+/-5.6 mm), ventricular septal wall thickness (resistance trained 9.7+/-1.0 mm versus control 10.1+/-0.7 mm), posterior wall thickness (resistance trained 9.6+/-1.5 mm versus control 9.3+/-1.4 mm) or LV mass (resistance trained 200. 3+/-32.5 g versus control 186.5+/-39.6 g). In addition, no resistance-trained athlete was found to have an LV mean wall thickness above clinical normal limits (12 mm or less). CONCLUSION: Contrary to common beliefs, long term resistance training as performed by elite male power-lifters does not alter LV morphology.

Adult↗

PubMed2000

Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular, and metabolic responses.

Most resistance training studies of older subjects have emphasized low-intensity, short-term training programs that have concentrated on strength measurements. The purpose of this study was, in addition to the determination of strength, to assess intramuscular and transport factors that may be associated with strength increments. Eighteen untrained men ages 60-75 years volunteered for the study; 9 were randomly placed in the resistance-training group (RT), and the other half served as untrained (UT) or control subjects. RT subjects performed a 16-week high-intensity (85-90% 1 repetition maximum (RT]) resistance training program (2 x/wk) consisting of 3 sets each to failure (6-8 repetitions based on 1 RM of 3 exercises): leg press (LP), half squat (HS), and leg extension (LE) with 1-2 minutes rest between sets. Pre- and post- training strength was measured for the 3 training exercises using a 1 RM protocol. Body fat was calculated using a 3-site skinfold method. Biopsies from the vastus lateralis m. were obtained for fiber type composition, cross-sectional area, and capillarization measurements. Exercise metabolism, electrocardiography, and arterial blood pressure were observed continuously during a progressive treadmill test, and resting echocardiographic data were recorded for all subjects. Pre- and post-training venous blood samples were analyzed for serum lipids. Resistance training caused significant changes in the following comparisons: % fat decreased in the RT group by almost 3%, strength improved for all exercises: LE = + 50.4%, LP = + 72.3%, HS = + 83.5%; type IIB fibers decreased and IIA fibers increased; cross-sectional areas of all fiber types (I, IIA, IIB) increased significantly, and capillary to fiber ratio increased but not significantly. No differences were noted for ECG and echocardiographic data. The RT group significantly improved treadmill performance and VO2max. Pre- and post-training serum lipids improved but not significantly. No significant changes occurred in any pre- to post-tests for the UT group. The results show that skeletal muscle in older, untrained men will respond with significant strength gains accompanied by considerable increases in fiber size and capillary density. Maximal working capacity, VO2max, and serum lipid profiles also benefited from high-intensity resistance training, but no changes were observed for HR max, or maximal responses of arterial blood pressure. Older men may not only tolerate very high intensity work loads but will exhibit intramuscular, cardiovascular, and metabolic changes similar to younger subjects.

Aerobiosis↗

PubMed2004

The effects of high- and moderate-resistance training on muscle function in the elderly.

The purpose of this study was to investigate the effects of a 12-week resistance-training program on muscle strength and mass in older adults. Thirty-three inactive participants (60-74 years old) were assigned to 1 of 3 groups: high-resistance training (HT), moderate-resistance training (MT), and control. After the training period, both HT and MT significantly increased 1-RM body strength, the peak torque of knee extensors and flexors, and the midthigh cross-sectional area of the total muscle. In addition, both HT and MT significantly decreased the abdominal circumference. HT was more effective in increasing 1-RM strength, muscle mass, and peak knee-flexor torque than was MT. These data suggest that muscle strength and mass can be improved in the elderly with both high- and moderate-intensity resistance training, but high-resistance training can lead to greater strength gains and hypertrophy than can moderate-resistance training.

Aged↗

PubMedDate not supplied

Resistance training and head-neck segment dynamic stabilization in male and female collegiate soccer players.

CONTEXT: Cervical resistance training has been purported to aid in reducing the severity of brain injuries in athletes. OBJECTIVE: To determine the effect of an 8-week resistance-training program on head-neck segment dynamic stabilization in male and female collegiate soccer players. DESIGN: Pretest and posttest control group design. SETTING: University research laboratory and fitness center. PATIENTS OR OTHER PARTICIPANTS: Thirty-six National Collegiate Athletic Association Division I collegiate soccer players (17 men, 19 women). INTERVENTION(S): The resistance training group underwent an 8-week cervical resistance training program that consisted of 3 sets of 10 repetitions of neck flexion and extension at 55% to 70% of their 10-repetition maximum 2 times a week. Participants in the control group performed no cervical resistance exercises. MAIN OUTCOME MEASURE(S): Head-neck segment kinematics and stiffness, electromyographic activity of the upper trapezius and sternocleidomastoid muscles during force application to the head, and neck flexor and extensor isometric strength. RESULTS: No kinematic, electromyographic, or stiffness training effects were seen. The posttest resistance training group isometric neck flexor strength was 15% greater than the pretest measurement. Isometric neck extensor strength in the female resistance training group was 22.5% greater at the posttest than at the pretest. Women's neck girth increased 3.4% over time regardless of training group level. Women exhibited 7% less head-neck segment length and 26% less head-neck segment mass than men. CONCLUSIONS: Despite increases in isometric strength and girth, the 8-week isotonic cervical resistance training did not enhance head-neck segment dynamic stabilization during force application in collegiate soccer players. Future researchers should examine the effect of head-neck segment training protocols that include traditional and neuromuscular activities (eg, plyometrics) with the focus of reducing head acceleration on force application.

Journal Article↗

PubMed2026

Photobiomodulation as an Adjunct to Resistance Training in Older Adults: A Systematic Review and Meta-Analysis.

BACKGROUND: Photobiomodulation (PBM) has been proposed as an adjunct to resistance training to enhance strength adaptations; however, findings from randomized controlled trials (RCTs) remain inconsistent. This study aimed to evaluate whether adjunctive PBM improves maximal strength gains when combined with periodized resistance training in older adults. METHODS: RCTs were identified through systematic searches of PubMed, Scopus, Embase, PEDro, Web of Science, the Cochrane Library, and CNKI from inception to January 2026. Eligible studies examined PBM delivered via low-level laser therapy or light-emitting diodes in combination with resistance training or other strength-oriented loading tasks. Prespecified meta-analyses were restricted to trials combining PBM with periodized resistance training that reported one-repetition maximum (1RM) outcomes; other studies were included in a narrative synthesis. RESULTS: Eleven RCTs (n = 456) were included. Five trials (PBM plus resistance training: n = 74; control: n = 72) met the criteria for meta-analysis. PBM combined with resistance training did not significantly improve maximal muscle strength compared with sham PBM (SMD = 0.26, 95% CI -0.08 to 0.59; p = 0.14; I2 = 4%). Subgroup analyses showed a nonsignificant trend favoring PBM for unilateral 1RM, with no effect for bilateral outcomes and no significant subgroup differences. Sensitivity analyses indicated that the unilateral effect was dependent on individual studies. In nonresistance training contexts, some studies reported potential benefits for fatigue-, recovery-, or function-related outcomes, particularly in frail or critically ill older adults, although findings were inconsistent. CONCLUSION: Current evidence does not demonstrate a clear additional benefit of PBM on maximal strength when combined with resistance training in older adults, although a small effect cannot be excluded. PBM may have selective value in improving recovery-related outcomes and supporting training tolerance in vulnerable populations. Larger, well-designed RCTs are needed to clarify its role.

Humans↗

PubMed1997

Chromium picolinate supplementation and resistive training by older men: effects on iron-status and hematologic indexes.

Chromium competes with iron for binding to transferrin, and high-dose chromium supplementation has been hypothesized to adversely affect iron status. This study examined the effects of chromium picolinate supplementation on hematologic indexes and selected indexes of iron status in 18 men aged 56-69 y who participated in an introductory resistive training program. The men were randomly assigned (double-blind design) to groups (n = 9) that consumed either 17.8 mumol Cr/d (924 micrograms Cr/d) as chromium picolinate or a low-chromium placebo for 12 wk while engaging in resistive training twice weekly (3 sets of 8-12 repetitions at 80% of one repetition maximum for 5 exercises). Hematocrit, hemoglobin, red blood cell (erythrocyte) count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red blood cell distribution width, platelet count, and mean platelet volume were within normal clinical ranges and were unchanged by either chromium picolinate supplementation or resistive training. Resistive training decreased total-iron-binding capacity from 38.4 +/- 9.3 to 27.3 +/- 5.6 mumol/L (P < 0.0001) and increased transferrin saturation from 35.7 +/- 16.3% to 45.4 +/- 16.9% (P = 0.050). Chromium picolinate supplementation did not influence these responses. Serum iron concentrations and serum ferritin concentrations were unchanged by either resistive training or chromium picolinate supplementation. These data suggest that high-dose chromium picolinate supplementation for 12 wk did not influence hematologic indexes or indexes of iron metabolism or status in older men. The decrease in total-iron-binding capacity and increase in transferrin saturation (%) with resistive training are largely opposite to changes associated with iron depletion and suggest a novel effect of resistive training on iron transport.

Aged↗

PubMed2000

IGF-1 bioavailability is increased by resistance training in older women with low bone mineral density.

We investigated if long-term resistance training would increase insulin-like growth factor-1 (IGF-1) bioavailabilty at rest in older women (68+/-1 years) with low bone mineral density. IGF-1 levels were significantly lower (P<0.05), and insulin-like growth factor binding proteins -1 and -3 (IGFBP-1 and IGFBP-3) significantly higher than an age-matched healthy normal group. Resistance training resulted in significant (P<0.05) increases in repetition maximums across all exercises (range 41-78%). Resting IGF-1 levels were significantly (P<0.05) elevated (70%) by the resistance training whereas no significant changes occurred in IGFBP-1 and IGFBP-3 levels. IGFBP-1/IGF-1 and IGFBP-3/IGF-1 ratios were significantly decreased (approximately - 50%) as a result of resistance training (P<0.05). Thus, IGF-1 bioavailability was increased as a result of resistance training induced increases in IGF-1 levels in older women with low bone mineral density. These alterations in the IGF-1 system may be contributing to the significant strength gain observed with the resistance training in this population.

Aged↗

PubMed2005

Does nutritional supplementation influence adaptability of muscle to resistance training in men aged 48 to 72 years.

BACKGROUND AND PURPOSE: Isotonic strength training can result in neuromuscular improvements evidenced in other forms of muscular effort, ie, isokinetic or isometric, especially in young subjects; however, it is unclear if older muscle maintains this same adaptive ability. Additionally, it is not known if the benefits of resistance training can be augmented by creatine and protein supplementation in older men. Therefore, the purpose of this study was to assess changes in isokinetic parameters at varying speeds in men aged 48 to 72 years (mean=57+/-2.1) following 16 weeks of isotonic resistance training and creatine and/or protein supplementation. METHODS: Forty-two male subjects were randomly assigned to 1 of 4 training groups: (1) resistance training placebo (n=10), (2) resistance trained creatine supplemented (n=10), (3) resistance trained protein supplemented (n=11), and (4) resistance trained creatine and protein supplemented (n=11). The program consisted of progressive overload resistance training (3 d/wk) and supplement consumption following the workout. RESULTS: There were significant time effects (P>.05) for peak torque (PT), time to PT, and average power for both the knee extensors and flexors at all velocities. However, no significant group or group by time interactions were noted, indicating that the supplementation protocols had no added benefits. CONCLUSIONS: Men aged 48 to 72 years maintained their ability to improve isokinetic muscle function following isotonic training, however, supplementation did not enhance muscle adaptability.

Adaptation, Physiological↗

PubMed1992

Resistance training during pre- and early puberty: efficacy, trainability, mechanisms, and persistence.

Resistance training, under conditions of high intensity and volume loading, is effective in increasing strength in pre- and early pubertal children. The mechanisms underlying strength gain with resistance training in this population have not been established unequivocally. However, resistance training appears to have little if any effect on muscle size (hypertrophy), but it has resulted in neurological (percent motor unit activation and increased integrated EMG activity) changes and changes in intrinsic muscle function (twitch torque), which could account for part of the training-induced increases in voluntary strength. Changes in motor skill coordination (synchronization of muscle action) probably also contribute substantially to resistance-training-induced strength increases in children, particularly for multijoint, complex strength manoeuvres. Most, but not all, studies indicate that pre- and early pubertal children make similar relative strength gains compared to adolescents and adults, but usually demonstrate smaller absolute strength gains following training. Training-induced strength gains appear to decay during detraining, and maintenance training consisting of only one training session per week appears to be ineffective in preserving prior strength gains.

Adaptation, Physiological↗

PubMed2002

Resistance training increases glucose uptake and transport in rat skeletal muscle.

The aim of this investigation was to determine if resistance training exercise improved glucose uptake and transport in rodent skeletal muscle. Sprague-Dawley rats were assigned to one of the three groups: control (CON), resistance trained (RT) and aerobic exercise trained (AT). Resistance trained rats were placed in a rodent squat apparatus and performed three sets of 10 repetitions at 75% of their one repetition maximum 3 days week-1 for 12 weeks. Aerobic exercise training consisted of running the rats 3 days week-1 for 45 min over a 12-week period on a motor-driven treadmill (32 m min-1, 15% grade). Following the training period, all animals were subjected to hind limb perfusion in the presence of 500 microU mL-1 insulin. Hind limb glucose uptake was similar in the RT (9.91 +/- 0.7 micromol g-1 h-1) and AT (10.23 +/- 1.0 micromol g-1 h-1) animals and significantly greater than control (CON) (6.40 +/- 0.6 micromol g-1 h-1). Rates of 3-O-methyl-d-glucose transport in the RT animals were elevated in the muscles utilized for RT while in the AT animals rates of 3-O-methyl-d-glucose transport were increased in those muscles recruited for running. The increased rates of 3-O-methyl-d-glucose transport in the skeletal muscles of the resistance trained and aerobic exercise trained animals appeared to be, in part, because of an increased GLUT4 protein concentration. These findings suggest that both resistance or aerobic training exercise can improve insulin-stimulated skeletal muscle glucose uptake and transport, but the training adaptations are restricted to the muscles recruited for the exercise performance.

3-O-Methylglucose↗

PubMed1996

Effect of resistance training on strength, postural control, and gait velocity among older adults.

The purpose of this study was to examine the effects of a 14-week resistance training program on the ankle strength, training intensity, postural control, and gait velocity of older adults. Forty-two older adults (mean age = 72), 21 in the resistance and control groups, completed the 14-week project. The resistance training group participated in 14 weeks of resistance training three times per week using elastic bands (Theraband) for resistance. Isokinetic ankle strength, training intensity, postural stability, and gait velocity were measured prior to and following the 14-week intervention. Following the training, the resistance group exhibited improved ankle dorsiflexion, training resistances, and gait velocity, but showed no change in plantar flexion or postural control. The control group also exhibited improvements in dorsiflexion, but these gains were approximately one-half of the gains observed in the resistance training group. Finally, when adjusted for baseline differences, subjects in the resistance training group demonstrated no changes in the dependent measures over the control group.

Age Factors↗

PubMed2005

Changes in the human muscle force-velocity relationship in response to resistance training and subsequent detraining.

Previous studies show that cessation of resistance training, commonly known as "detraining," is associated with strength loss, decreased neural drive, and muscular atrophy. Detraining may also increase the expression of fast muscle myosin heavy chain (MHC) isoforms. The present study examined the effect of detraining subsequent to resistance training on contractile performance during slow-to-medium velocity isokinetic muscle contraction vs. performance of maximal velocity "unloaded" limb movement (i.e., no external loading of the limb). Maximal knee extensor strength was measured in an isokinetic dynamometer at 30 and 240 degrees/s, and performance of maximal velocity limb movement was measured with a goniometer during maximal unloaded knee extension. Muscle cross-sectional area was determined with MRI. Electromyographic signals were measured in the quadriceps and hamstring muscles. Twitch contractions were evoked in the passive vastus lateralis muscle. MHC isoform composition was determined with SDS-PAGE. Isokinetic muscle strength increased 18% (P < 0.01) and 10% (P < 0.05) at slow and medium velocities, respectively, along with gains in muscle cross-sectional area and increased electromyogram in response to 3 mo of resistance training. After 3 mo of detraining these gains were lost, whereas in contrast maximal unloaded knee extension velocity and power increased 14% (P < 0.05) and 44% (P < 0.05), respectively. Additionally, faster muscle twitch contractile properties along with an increased and decreased amount of MHC type II and MHC type I isoforms, respectively, were observed. In conclusion, detraining subsequent to resistance training increases maximal unloaded movement speed and power in previously untrained subjects. A phenotypic shift toward faster muscle MHC isoforms (I --> IIA --> IIX) and faster electrically evoked muscle contractile properties in response to detraining may explain the present results.

Adaptation, Physiological↗