Lower Body Muscle Groups Research Articles

Task-oriented exercise effects on walking and corticospinal excitability in multiple sclerosis: protocol for a randomized controlled trial

BackgroundMultiple sclerosis (MS) is a degenerative disease of the central nervous system (CNS) that disrupts walking function and results in other debilitating symptoms. This study compares the effects of ‘task-oriented exercise’ against ‘generalized resistance and aerobic exercise’ and a ‘stretching control’ on walking and CNS function in people with MS (PwMS). We hypothesize that task-oriented exercise will enhance walking speed and related neural changes to a greater extent than other exercise approaches.MethodsThis study is a single-blinded, three-arm randomized controlled trial conducted in Saskatchewan, Canada. Eligible participants are those older than 18 years of age with a diagnosis of MS and an expanded Patient-Determined Disease Steps (PDDS) score between 3 (‘gait disability’) and 6 (‘bilateral support’). Exercise interventions are delivered for 12 weeks (3 × 60-min per week) in-person under the supervision of a qualified exercise professional. Interventions differ in exercise approach, such that task-oriented exercise involves weight-bearing, walking-specific activities, while generalized resistance and aerobic exercise uses seated machine-based resistance training of major upper and lower body muscle groups and recumbent cycling, and the stretching control exercise involves seated flexibility and relaxation activities. Participants are allocated to interventions using blocked randomization that stratifies by PDDS (mild: 3–4; moderate: 5–6). Assessments are conducted at baseline, post-intervention, and at a six-week retention time point. The primary and secondary outcome measures are the Timed 25-Foot Walk Test and corticospinal excitability for the tibialis anterior muscles determined using transcranial magnetic stimulation (TMS), respectively. Tertiary outcomes include assessments of balance, additional TMS measures, blood biomarkers of neural health and inflammation, and measures of cardiorespiratory and musculoskeletal fitness.DiscussionA paradigm shift in MS healthcare towards the use of “exercise as medicine” was recently proposed to improve outcomes and alleviate the economic burden of MS. Findings will support this shift by informing the development of specialized exercise programming that targets walking and changes in corticospinal excitability in PwMS.Trial registrationClinicalTrials.gov, NCT05496881, Registered August 11, 2022. https://classic.clinicaltrials.gov/ct2/show/NCT05496881. Protocol amendment number: 01; Issue date: August 1, 2023; Primary reason for amendment: Expand eligibility to include people with all forms of MS rather than progressive forms of MS only.

Upper-lower body super-sets vs. traditional sets for inducing chronic athletic performance improvements.

To promote chronic adaptations, resistance training needs the manipulation of different variables, among them, the order of the exercises and sets. Specifically, for velocity-based training, paired exercises alternating upper and/or lower-body muscle groups appear to be a good choice to promote neuromuscular adaptations. This study aimed to compare the effect of two velocity-based training programs only differing in the set configuration on muscle strength, muscular endurance and jump performance. Moderately strength-trained men were allocated into a traditional (TS, n= 8) or alternating sets (AS, n= 9) configuration group to perform a 6-week velocity-based training program using the full squat (SQ) and bench press (BP) exercises. The TS group completed all sets of the full squat (SQ) exercise before performing the bench press (BP) sets, whereas the AS group completed the first set of each exercise in an alternating manner. Training frequency, relative load, number of sets, percentage of velocity loss (%VL) within the set and inter-set rest were matched for both groups. Countermovement jump height (CMJ), load (kg)-velocity relationship, predicted 1RM, and muscular endurance for each exercise were evaluated at pre- and post-training. The TS and AS groups obtained similar and non-significant improvements in CMJ (3.01 ±4.84% and 3.77 ±6.12%, respectively). Both groups exhibited significant and similar increases in muscle strength variables in SQ (6.19-11.55% vs. 6.90-011.76%; p=0.033-0.044, for TS and AS, respectively), BP (6.19-13.87% and 3.99-9.58%; p=0.036-0.049, for TS and AS group, respectively), and muscular endurance in BP (7.29 ±7.76% and 7.72 ±9.73%; p=0.033, for the TS and AS group, respectively). However, the AS group showed a greater improvement in muscular endurance in SQ than the TS group (10.19 ±15.23% vs. 2.76 ±7.39%; p=0.047, respectively). Total training time per session was significantly shorter (p=0.000) for AS compared to TS group. Training programs performing AS between SQ and BP exercises with moderate loads and %VL induce similar jump and strength improvements, but in a more time-efficient manner, than the traditional approach.

Effects of Postactivation Potentiation on Maximal Vertical Jump Performance After a Conditioning Contraction in Upper-Body and Lower-Body Muscle Groups.

Downey, RJ, Deprez, DA, and Chilibeck, PD. Effects of postactivation potentiation on maximal vertical jump performance after a conditioning contraction in upper-body and lower-body muscle groups. J Strength Cond Res 36(1): 259-261, 2022-Postactivation potentiation (PAP) involves preperformance contractions that can condition a muscle to enhance subsequent force generation and power output. Our purpose was to examine the effects of conditioning contractions that are specific or nonspecific to the target performance on PAP. Resistance-trained subjects (14 males and 10 females) performed a 7-second isometric contraction involving back squat, bench press (as conditioning contractions), or a control condition (rest) on different days in random order, before maximal vertical jump performance. The back squat as a conditioning contraction increased maximal vertical jump by 1.1 ± 3.0 cm (p < 0.05); however, the bench press as a conditioning contraction unexpectedly reduced maximal vertical jump performance by 1.4 ± 2.7 cm (p < 0.05). Conditioning contractions used to elicit a PAP response should use muscles that are specific to the performance movement. Contractions that are not biomechanically similar to the performance movement may hinder subsequent performance.

Neuromuscular and physiological assessment during a vertical jumping test in aerobic gymnastics

In executing aerobic gymnastics technical elements, a high level of explosive power is needed, especially at lower-body muscle groups. In addition, to maintain the specific effort during routine length (1 min 30 s - 1 min 45 s), an optimal development of specific endurance training and a high capacity of focusing is required, in order to execute the technical elements with accuracy. The purpose of this study was to elaborate a testing protocol to evaluate the physical effort capacity necessary to perform specific technical elements in aerobic gymnastics. The proposed testing protocol, is aimed at assessing neuromuscular behavior of lower-body muscle action and the physiological demands, in a maximal vertical jump test (MVJ). The neuromuscular assessment of the of lower-body was achieved by measuring the specific vertical jump parameters, respectively the power in the take-off phase (P) and the height of the jump (JH). The testing protocol consisted of three sets of maximum vertical jumps, lasting 30 s each, with a 15 s rest time between sets. For the physiological demands, as a result of test implementation, heart rate (HR) and the blood lactate concentration (La) were measured. The study was conducted on a group of 13 junior level gymnasts, 7 females and 6 males (aged 14-16 years, average height 163 SD 8.1 cm, average weight 50.69 SD 8.47 kg). The results of this study confirm the proposed methodology reflects an objective view of the physical training status necessary for specific effort accomplishment in aerobic performance gymnastics.

Prehabilitation Telemedicine in Neoadjuvant Surgical Oncology Patients During the Novel COVID-19 Coronavirus Pandemic

Prehabilitation Telemedicine in Neoadjuvant Surgical Oncology Patients During the Novel COVID-19 Coronavirus Pandemic

Movement Analysis of Philippine Folk Dance Tinikling

The purpose of the study was to describe the dance movements of the folk dance Tinikling which is the most popular traditional dance and former national dance of the Philippines. The researchers adopted the movement analysis method similar to that of Mackenzie that involves the (1) description of the actual movements which occur at the joints involved; (2) the plane in which the movement occurs; and (3) the muscles producing the movement (agonist &amp; antagonist). In addition, the researchers also had done a mechanical analysis on the lever type involved in the execution of the dance movement in terms of force, axis, and resistance. The prominent dance steps in the Philippine local dance Tinikling are the (1) running, (2) tinikling steps, (3) diagonal step, and (4) straddle jump with a turn step. The joints involved are: hip muscle which is ball and socket type of joint; and knee and ankle which are hinge joints. The major muscles involved in the dance include mostly the lower body muscle groups such as the quadriceps, hamstring, gluts, adductor muscle group, and calves. The type of lever used in performing the dance comprise majority of 1st, 2nd and 3rd class levers. Thus, the Tinikling is a viable dance which could improve the health related fitness of the performers in terms of muscular strength, muscular endurance, cardiovascular endurance and flexibility. Also, the dance could improve skill-related fitness such as power, agility, balance and coordination.

Effect of resistance training set volume on upper body muscle hypertrophy: are more sets really better than less?

Resistance training (RT) for upper body muscle hypertrophy (UBMH) typically entails high volumes of sets per muscle group per training session. The majority of RT regimens does not discriminate between upper and lower body muscle groups, while these groups may respond differently to RT set volumes in terms of maximum skeletal muscle mass gain. Recent studies have examined the effect of different set volumes on the extent of UBMH to formulate optimal RT regimens and to make RT programmes more time-efficient. To analyse the effect of the number of RT sets on the extent of UBMH on the basis of recent literature. The analysis suggests that, statistically, high set volumes (≥3) are not significantly better than low set volumes (<3) in regard to UBMH in untrained subjects. For trained subjects, the literature is lacking in well-designed studies comparing low and high training volumes, as well as analysing upper and lower body muscles separately. Therefore, it is not possible to conclude that high volume of sets offers better results than low volume of sets for UBMH, and vice versa.

Relation between Peak Power Output in Sprint Cycling and Maximum Voluntary Isometric Torque Production

From a cycling paradigm, little has been done to understand the relationships between maximal isometric strength of different single joint lower body muscle groups and their relation with, and ability to predict PPO and how they compare to an isometric cycling specific task. The aim of this study was to establish relationships between maximal voluntary torque production from isometric single-joint and cycling specific tasks and assess their ability to predict PPO. Twenty male trained cyclists participated in this study. Peak torque was measured by performing maximum voluntary contractions (MVC) of knee extensors, knee flexors, dorsi flexors and hip extensors whilst instrumented cranks measured isometric peak torque from MVC when participants were in their cycling specific position (ISOCYC). A stepwise regression showed that peak torque of the knee extensors was the only significant predictor of PPO when using SJD and accounted for 47% of the variance. However, when compared to ISOCYC, the only significant predictor of PPO was ISOCYC, which accounted for 77% of the variance. This suggests that peak torque of the knee extensors was the best single-joint predictor of PPO in sprint cycling. Furthermore, a stronger prediction can be made from a task specific isometric task.

A randomised controlled trial of resistance exercise prior to administration of influenza vaccination in older adults

The low rate of vaccine efficacy in the older adult population poses a major challenge to public health. Previous investigation has found acute exercise can enhance immune responses to vaccines within a young adult population. To date, no study has investigated the effect of exercise on vaccine responses in immune-compromised groups such as older adults, a group who could potentially benefit from enhanced responses. Forty-six healthy older adults (mean age = 73 ± 7 years, BMI = 27.2 ± 5 kg m2, male = 23) were randomly assigned to complete a control or exercise task prior to administration of the seasonal influenza vaccine. The exercise group performed resistance exercises using upper and lower body muscle groups at an intensity of 60-percent one repetition maximum. Antigen-specific serum antibody titres were measured at baseline and one-month and six-months post-vaccination. Exercise task elicited expected changes in inflammatory markers, but for all three viral strains of the influenza vaccine, changes in antibody titre from baseline to one-month and six-months post vaccination were similar between groups who exercised prior to vaccination and those who rested. Control participants suffered a higher rate of systemic adverse events in the 48 h following vaccination. To our knowledge, this was the first randomised controlled trial (RCT) investigating the effects of resistance exercise on vaccine response in the older adult population, limitations include sample size and intensity of exercise task which may have contributed to the null finding.

Effect of caffeine ingestion on maximal voluntary contraction strength in upper- and lower-body muscle groups.

The effect of caffeine on strength-power performance is equivocal, especially with regard to maximal voluntary contraction (MVC) strength. This is partly related to differences in upper- and lower-body musculature. However, there is no evidence to suggest whether this is a product of muscle group location, muscle group size, or both. Consequently, the primary aim of this study was to establish whether the effect of caffeine ingestion on MVC strength in upper- and lower-body muscle groups is significantly different, and if so, to determine whether this is a product of muscle group size. In a randomized, subject-blind crossover manner, 16 resistance-trained men (estimated caffeine intake [mean ± SD] 95.4 ± 80.0 mg·d) received either 6 mg·kg of caffeine (CAF) or a placebo (PLA). Isokinetic peak torque of the knee extensors, ankle plantar flexors, elbow flexors and wrist flexors were measured at an angular velocity of 60°·s. Statistical analyses revealed a significant increase in isokinetic peak torque from PLA to CAF (p = 0.011) and a significant difference in isokinetic peak torque between muscle groups (p < 0.001). However, there was no significant treatment × muscle group interaction (p = 0.056). Nonetheless, the %improvement in isokinetic peak torque with caffeine increased with muscle group size. In conclusion, a moderate dose of caffeine improves MVC strength in resistance-trained men regardless of muscle group location, whereas the influence of muscle group size remains uncertain. This research may be useful for competitive and recreational athletes aiming to increase strength-power performance.

Cardiac autonomic profile and cardiopulmonary response after maximal treadmill exercise testing with pre-exercise stretching

ObjectivesThis study investigated the cardiac autonomic profile and cardiopulmonary responses at rest and after maximal treadmill exercise testing with or without pre-exercise stretching. MethodsEight men (age = 24.6 ±mm 5.5 years; height = 179 ±mm 4.1cm; mass = 78.1 ±mm 3.4kg; body mass index = 24 ±mm 2.5kg/m−2; body fat = 18.9 #mm 4.3%) completed a maximal treadmill exercise test under two randomly ordered conditions: pre-exercise stretching (PES) and no stretching (CONTROL). Electrocardiogram (ECG) and respired gas analysis were continuously recorded at rest, during, and for 5 min following exercise testing. The stretching exercises for the PES condition consisted of six passive stretches comprising upper and lower body muscle groups performed three times each for 30 sec with 10 sec passive rest between repetitions. ResultsThe results indicated that the rMSSD was significantly (p<0.01) faster for the CONTROL versus the PES condition during the 5 min following exercise testing. Additionally, significantly lower low-frequency power (PES = 3.20 ±mm 1.14ms2; CONTROL= 24.65 ±mm 7.57ms2; p<0.001) and total power (PES = 23.57 ±mm 7.41ms2; CONTROL = 195.90 ±mm 46.37 ms2; p<0.001) responses were visually detected for the PES versus CONTROL condition following exercise testing. Anaerobic threshold was decrease in PES when compared to CONTROL conditions. Conclusion. These data indicate that PES promotes dysfunction in the tonic cardiac autonomic regulation as evidenced by delayed parasympathetic reactivation, during the initial 5 minutes of recovery following maximal exercise testing.

Efeitos do treinamento aeróbio e resistido nas respostas cardiovasculares de idosos ativos

OBJETIVO: Verificar os efeitos da associação do treinamento aeróbio e resistido nas respostas cardiovasculares de idosos. MÉTODOS: Onze sujeitos (ambos os gêneros, 70 ± 5 anos) realizaram, duas vezes por semana, caminhada e exercícios resistidos para membros inferiores por 12 semanas. As avaliações foram realizadas antes, a cada quatro semanas de treinamento e após quatro semanas de destreinamento, por meio do teste de seis minutos de caminhada e aferição de pressão arterial (PA) e frequência cardíaca (FC) antes, imediatamente após e no quinto e décimo minutos subsequentes ao teste. Os resultados foram comparados pelo teste Wilcoxon (p ≤ 0,05). RESULTADOS: Quatro semanas de treinamento promoveram redução da PA sistólica e diastólica em repouso (120 ± 16 mmHg vs. 138 ± 20 mmHg, p = 0,01; 70 ± 9 mmHg vs. 84 ± 10 mmHg, p = 0,007, respectivamente) e redução da PA diastólica imediatamente após o teste (78 ± 12 mmHg vs. 86 ± 9 mmHg, p = 0,01), que persistiu após dez minutos do esforço submáximo, quando comparadas ao pré-treino. Após 12 semanas, houve aumento da distância percorrida (555 ± 65m vs. 514 ± 100 m, p = 0,04) quando comparado ao pré-treino e recuperação dos valores de repouso da FC dez minutos após o esforço. CONCLUSÃO: A associação do treinamento aeróbio e resistido, em apenas quatro semanas, promoveu adaptações cardiovasculares eficientes na redução da PA sistólica e diastólica. Após 12 semanas, houve aumento da resistência à caminhada submáxima e recuperação dos valores em repouso da FC. Mesmo com o destreinamento, todos os resultados, exceto a FC, foram mantidos.

Strength exercise improves muscle mass and hepatic insulin sensitivity in obese youth.

Data on the metabolic effects of resistance exercise (strength training) in adolescents are limited. The objective of this study was to determine whether a controlled resistance exercise program without dietary intervention or weight loss reduces body fat accumulation, increases lean body mass, and improves insulin sensitivity and glucose metabolism in sedentary obese Hispanic adolescents. Twelve obese adolescents (age = 15.5 ± 0.5 yr, body mass index = 35.3 ± 0.8 kg·m; 40.8% ± 1.5% body fat) completed a 12-wk resistance exercise program (two times 1 h·wk, exercising all major muscle groups). At baseline and on completion of the program, body composition was measured by dual-energy x-ray absorptiometry, abdominal fat distribution was measured by magnetic resonance imaging, hepatic and intramyocellular fat was measured by magnetic resonance spectroscopy, peripheral insulin sensitivity was measured by the stable-label intravenous glucose tolerance test, and hepatic insulin sensitivity was measured by the hepatic insulin sensitivity index = 1000/(GPR × fasting insulin). Glucose production rate (GPR), gluconeogenesis, and glycogenolysis were quantified using stable isotope gas chromatography/mass spectrometry techniques. All participants were normoglycemic. The exercise program resulted in significant strength gain in both upper and lower body muscle groups. Body weight increased from 97.0 ± 3.8 to 99.6 ± 4.2 kg (P < 0.01). The major part (∼80%) was accounted for by increased lean body mass (55.7 ± 2.8 to 57.9 ± 3.0 kg, P ≤ 0.01). Total, visceral, hepatic, and intramyocellular fat contents remained unchanged. Hepatic insulin sensitivity increased by 24% ± 9% (P < 0.05), whereas peripheral insulin sensitivity did not change significantly. GPR decreased by 8% ± 1% (P < 0.01) because of a 12% ± 5% decrease in glycogenolysis (P < 0.05). We conclude that a controlled resistance exercise program without weight loss increases strength and lean body mass, improves hepatic insulin sensitivity, and decreases GPR without affecting total fat mass or visceral, hepatic, and intramyocellular fat contents.

Effects of Static Stretching on Energy Cost and Running Endurance Performance

Stretching before anaerobic events has resulted in declines in performance; however, the immediate effects of stretching on endurance performance have not been investigated. This study investigated the effects of static stretching on energy cost and endurance performance in trained male runners. Ten trained male distance runners aged 25 +/- 7 years with an average VO2max of 63.8 +/- 2.8 ml/kg/min were recruited. Participants reported to the laboratory on 3 separate days. On day 1, anthropometrics and VO2max were measured. On days 2 and 3, participants performed a 60-minute treadmill run randomly under stretching or nonstretching conditions separated by at least 1 week. Stretching consisted of 16 minutes of static stretching using 5 exercises for the major lower body muscle groups, whereas nonstretching consisted of 16 minutes of quiet sitting. The run consisted of a 30-minute 65% VO2max preload followed by a 30-minute performance run where participants ran as far as possible without viewing distance or speed. Total calories expended were determined for the 30-minute preload run, whereas performance was measured as distance covered in the performance run. Performance was significantly greater in the nonstretching (6.0 +/- 1.1 km) vs. the stretching (5.8 +/- 1.0 km) condition (p < 0.05), with significantly greater energy expenditure during the stretching compared with the nonstretching condition (425 +/- 50 vs. 405 +/- 50 kcals). Our findings suggest that stretching before an endurance event may lower endurance performance and increase the energy cost of running.

Effect Of Single Vs Multiple Sets Of Resistance Exercise On Muscle Strength

Most studies reported that performing resistance training with multiple sets per training session is more effective for increasing strength as training with a single set. However, only few studies compared the effects of single vs. multiple sets on strength between small vs. large muscle groups, and upper-body vs. lower-body muscle groups. PURPOSE: The purpose of this study was to determine the effect of single sets vs. multiple sets, during the early phase of adaptation, on different muscle group strength in untrained subjects. METHODS: Twenty six apparently healthy, untrained male participated in the study protocol. The volunteers were randomly assigned into one of two groups: 1) elbow flexion single set and knee extension three sets (E1-K3; n=13; 22.5 yrs), or 2) elbow flexion three sets and knee extension single set (E3-K1; n=1 3; 23.4 yrs). Subjects trained 2 days per week for 6 weeks and each workout consisted of 1 close chain knee extension exercise and 1 elbow flexion exercise. Training intensity varied between 8 repetition maximum (RM) and 12RM. Unilateral knee extension and elbow flexion strength were tested for both groups at 60°/s on a Biodex System 3 isokinetic dynamometer. Strength was expressed as peak torque (PT). Statistical evaluation of the data was measured using a 2 × 2 analysis of variance [group (E1-K3 and E3-K1) x time (pre and post)]. The probability level of statistical significance was set at p < 0.05 in all comparisons. RESULTS: The increase in PT of the knee extensors muscles from week 0 to 6 was significantly higher in the E1-K3 group (10.29%) than in the E3-K1 (3.78%) group, while no difference existed in PT gains between E1-K3 (7.75%) and E3-K1 (7.44%) of the elbow flexors muscles. CONCLUSIONS: It was concluded that performing three sets of strength training is superior to one set for increasing strength of the knee extensors muscles. It was also concluded that single-set training protocols for the elbow flexors muscles might be sufficient for untrained individuals in the early phases of a strength-training program.

Alterations in Muscle Attenuation following Detraining and Retraining in Resistance-Trained Older Adults

Background: Aging skeletal muscle is characterized not only by a reduction in size (sarcopenia) and strength but also by an increase in fatty infiltration (myosteatosis). An effective countermeasure to sarcopenia is resistance exercise; however, its effect on fatty infiltration is less clear. Objective: To examine in resistance-trained older persons whether muscle attenuation, a noninvasive measure of muscle density reflecting intramuscular lipid content, is altered with training status. Methods: Thirteen healthy community-dwelling men and women aged 65–83 years (body mass index 27.0 ± 1.2, mean ± SE) had computed-tomography scans of the mid-thigh performed following 24 weeks of training, 24 weeks of detraining, and 12 weeks of retraining. Training and retraining were undertaken twice weekly for several upper- and lower-body muscle groups. Skeletal muscle attenuation in Hounsfield units (HU) as well as mid-thigh muscle volume was obtained for the quadriceps and hamstrings. Muscle strength was assessed by 1-repetition maximum and physical function by a battery of tests. Results: The average change in muscle strength following training, detraining and retraining was 48.8 ± 2.9%, –17.6 ± 1.3%, and 19.8 ± 2.0%, respectively. Strength changes were accompanied by significant alterations in muscle density (p < 0.001), with the quadriceps HU decreasing by 7.7 ± 1.0% following detraining and increasing by 5.4 ± 0.5% with retraining. For the hamstrings HU measure, detraining and retraining resulted in an 11.9 ± 1.4% loss and a 5.5 ± 1.8% gain, respectively. There was no significant change in muscle volume. Conclusion: Cessation of resistance exercise in trained older persons increases the fatty infiltration of muscle, while resumption of exercise decreases it. Monitoring changes in both muscle size and fat infiltration may enable a more comprehensive assessment of exercise in combating age-related muscular changes.

Rowing Ergometer Training During Five Weeks of Head-Down Tilt Bedrest Preserves Cardiac Work and LV Mass

Exercise training in space or during bedrest which recruits both upper and lower body muscle groups may preserve cardiac work and thereby LV structure. PURPOSE: Examine whether rowing ergometry via a periodized exercise training program will not only preserve but increase cardiac work and LV mass. METHODS: Fifteen subjects (14 men and 1 woman, age 20-55 yr) were studied before, during and immediately after 5 weeks of −6° head-down tilt (HDT) bed rest. The subjects were divided into two groups: (1) bed rest without exercise, but sitting upright 45 minutes/day quietly on the ergometer (n=3); (2) bed rest with exercise (30-45 minutes/day, 6 days/week of exercise on a rowing ergometer in addition to 2 days/week of supine resistance training) (n=12). The endurance training included three days of exercise at a moderate, base pace and two days of high intensity interval training followed by a recovery day of intensity below base pace. Ambulatory systolic blood pressure and heart rate were measured over 24 hours before, during and after bed rest (Suntech Accutracker). Stroke volume was measured via acetylene rebreathing technique. Cardiac work was calculated as a product of stroke volume, heart rate, systolic blood pressure and time. RESULTS: Cardiac work of subjects who trained during bed rest was maintained to levels measured prior to bed rest (7.64 + 3.02 vs. 7.71 + 2.14, e08ml·mmHg·day−1). However, the cardiac work of nonexercising subjects decreased during bed rest (7.70 + 1.45 vs. 6.46 + 0.79, e08ml·mmHg·day−1). LV mass was preserved among the exercisers (154 + 58 vs. 157 + 50mg) yet decreased in the non-exercising group (124 + 10 vs. 117 + 1mg). CONCLUSIONS: Cardiac work was preserved in subjects who performed 30-45 min/day of dynamic, rowing exercise combined with resistance training during HDT bed rest. This preservation of cardiac work prevented the cardiac atrophy associated with 5 weeks of bed rest deconditioning. Supported by NASA grant CA00701.

The Effect of Moderate Resistance Strength Training and Detraining on Muscle Strength and Power in Older Men

The purpose of the present study was to evaluate the effects of 10 weeks of moderate resistance strength training followed by 6 weeks of detraining on muscle strength and jump performance in healthy, moderately active, older men, aged 61 - 75 years (mean age 68 +/- 5 years). Subjects were randomly assigned to a moderate resistance strength training group (RT, n = 9), or to a control group (C, n = 9). The RT group trained upper and lower body muscle groups at 60% of 1-Repetition Maximum (1-RM), 3 times per week for 12 weeks. Both groups were evaluated in the 1-RM knee extension and flexion strength, squat jump (SJ), and countermovement jump (CMJ) height before and after the training period. In addition, the RT group was evaluated in the same measurements after 6 weeks of detraining. After the training period, RT improved significantly (p < 0.001) the 1-RM knee extension (32%) and flexion (28%) strength, SJ (39%), and CMJ (31%) height. Significant reductions were observed in 1-RM lower body strength, SJ, and CMJ height by approximately 15%, after the detraining period. Muscle strength and vertical jump performance improved after short-term moderate resistance strength training. A short-term detraining period affects the muscle strength and power in older adults, but the neuromuscular function does not return to pretraining levels. This suggests that the continuation of a strength training program is essential for the maintenance of muscle strength, functional performance, and independence in older adults.

Endocrine and immune responses to resistance training in prostate cancer patients

This study examined the effect of 20 weeks resistance training on a range of serum hormones and inflammatory markers at rest, and following acute bouts of exercise in prostate cancer patients undergoing androgen deprivation. Ten patients exercised twice weekly at high intensity for several upper and lower-body muscle groups. Neither testosterone nor prostate-specific antigen changed at rest or following an acute bout of exercise. However, serum growth hormone (GH), dehydroepiandrosterone (DHEA), interleukin-6, tumor necrosis factor-alpha and differential blood leukocyte counts increased (P < 0.05) following acute exercise. Resistance exercise does not appear to compromise testosterone suppression, and acute elevations in serum GH and DHEA may partly underlie improvements observed in physical function.

The Effects of Betaine Supplementation on Strength and Power Performance

Betaine (B) is an organic osmolyte and methyl donor. Organic osmolytes are important for fluid balance during osmotic stress and metabolic methylation reactions. Both are important during resistance exercise given the flux of substrates through metabolic pathways and may benefit strength and power performance. PURPOSE: To determine the efficacy of B supplementation in improving strength and power performance. METHODS: Twelve men (mean ± SD age, 21 ± 3 yr; mass, 79.1 ± 10.7 kg) with a minimum of 3 months resistance training, including the squat exercise, completed two 14-day trials in a balanced, randomized, double-blind, repeated measures, crossover design. Prior to and following 14 days of B supplementation (1.25 g mixed in 240 ml Gatorade®) or placebo (P), consumed twice per day, subjects completed two consecutive days (D1 and D2) of a standardized high intensity/power resistance exercise challenge (REC). A 14-day washout period separated the 14-day B and P trials. Two standardized resistance training workouts were completed during B and P trials, and during the washout period, to maintain the subject's training status. Total body water was measured via multi-frequency bio-electrical impedance spectroscopy. ANOVA were conducted with alpha set at 0.05. RESULTS: Body mass and total body water values did not change over the course of the study. Following 14-days of B supplementation, bench throw power (1779 ± 90 W) and isometric bench press force (2922 ± 297 N) increased (p<0.05) during REC compared to pre-supplementation values and corresponding P values (1535 ± 81 W, 2345 ± 146 N, respectively). Compared to pre-supplementation, vertical jump power and isometric squat force increased (p<0.05) on both D1 and D2. There were no differences in bench press repetitions, number of squat repetitions, and jump squat power between D1 and D2, or between B and P values. CONCLUSION: B supplementation increased power, force and maintenance, particularly in the smaller upper-body muscle groups compared to larger lower-body muscle groups. Funded by Danisco USA Incorporated, Ardsley, NY.