Low serum brain-derived neurotrophic factor may predict poor response to cardiac rehabilitation in patients with cardiovascular disease.

BACKGROUND: It has been shown that serum brain-derived neurotrophic factor (BDNF) is associated with skeletal muscle energy metabolism and that BDNF is a predictor of mortality in heart failure patients. However, little is known about the relationship between BDNF and cardiac rehabilitation (CR). Therefore, this study retrospectively investigated the effects of baseline serum BDNF levels on the CR-induced exercise capacity improvement in patients with cardiovascular disease (CVD). METHODS: We assigned 99 CVD patients (mean age 71±12 years, male = 60) to Low, Middle, and High groups based on the tertiles of baseline BDNF levels. Cardiopulmonary exercise testing was done using supervised bicycle ergometer twice before and after 3 weeks of CR. Analysis of covariance (ANCOVA) followed by post-hoc analysis using Tukey's HSD test was conducted to assess the multivariate associations between baseline BDNF levels categorized by BDNF tertiles (as independent variable) and %increases in AT and peak VO2 after 3-week CR (as dependent variables) after adjustment for age and gender (as covariates), as a main statistical analysis of the present study. RESULTS: The higher the baseline BDNF levels, the better nutritional status evaluated by the CONUT score (p<0.0001). Baseline anaerobic threshold (AT) and peak oxygen uptake (peak VO2) were similar among the three groups. ANCOVA followed by post-hoc analysis revealed that age- and gender-adjusted %increases in peak VO2 after 3-week CR were positively associated with baseline BDNF levels (p = 0.0239) and Low BDNF group showed significantly lower %increase in peak VO2 than High BDNF group (p = 0.0197). Significant association was not found between baseline BDNF and %increase in AT (p = 0.1379). CONCLUSIONS: Low baseline BDNF levels were associated with malnutrition in CVD patients. A positive association between baseline BDNF levels and CR-induced increases in peak VO2 was found. It was suggested that CVD patients with low baseline BDNF levels may be poor responders to CR.

Effect of Cycling Exercise Resisting Electrically Stimulated Antagonist Muscle Contractions in Healthy Males.

A hybrid training system (HTS) combining antagonist muscle electrical stimulation and voluntary muscle contraction has been developed using eccentric antagonist muscle contractions with electrical stimulation as resistance to voluntary muscle contractions. We devised an exercise method using HTS combined with a cycle ergometer (HCE). The purpose of this study was to compare the muscle strength, muscle volume, aerobic functions and lactate metabolism of HCE and a volitional cycle ergometer (VCE). A total of 14 male participants performed exercise on a bicycle ergometer for 30 min per session, 3 times per week for 6 weeks. We divided 14 participants into an HCE group (7 participants) and a VCE group (7 participants). The workload was set at 40% of each participant's peak oxygen uptake (V.O2peak). Electrodes were placed over each motor point on the quadriceps and hamstrings. The V.O2peak and anaerobic threshold significantly increased before and after training when using HCE rather than VCE. The HCE group had significantly increased extension and flexion muscle strength at 180 degrees/s in post-training measurements over pre-training measurements. Knee flexion muscle strength at 180 degrees/s tended to increase in the HCE group compared to the VCE group. The quadricep muscle cross-sectional area was significantly increased in the HCE group compared to the VCE group. Additionally, the HCE group had significantly decreased maximal lactate, measured every 5 min during exercise at the end of study, between pre and post-training. Thus, HCE may be a more effective training method for muscle strength, muscle mass and aerobic functions at 40% of each participant's V.O2peak than conventional cycling exercise. HCE could be applied not only as aerobic exercise but also as resistance training.

Balance dysfunction the most significant cause of in-hospital falls in patients taking hypnotic drugs: A retrospective study.

PURPOSE: Preventing falls in patients is one of the most important concerns in acute hospitals. Balance disorder and hypnotic drugs lead to falls. The Standing Test for Imbalance and Disequilibrium (SIDE) is developed for the evaluation of static standing balance ability. There have been no reports of a comprehensive assessment of falls risk including hypnotic drugs and SIDE. The purpose of this study was to investigate the fall rate of each patient who took the hypnotic drug and the factor associated with falls. METHODS: Fall rates for each hypnotic drug were calculated as follows (number of patients who fell/number of patients prescribed hypnotic drug x 100). We investigated the hypnotic drugs as follows; benzodiazepine drugs, Z-drugs, melatonin receptor agonists, and orexin receptor antagonists. Hypnotic drug fall rate was analyzed using Pearson's chi-square test. Decision tree analysis is the method we used to discover the most influential factors associated with falls. RESULTS: This study included 2840 patients taking hypnotic drugs. Accidents involving falls were reported for 211 of inpatients taking hypnotic drugs. Z-drug recipients had the lowest fall rate among the hypnotic drugs. We analyzed to identify independent factors for falls, a decision tree algorithm was created using two divergence variables. The SIDE levels indicating balance disorder were the initial divergence variable. The rate of falls in patients at SIDE level ≦ 2a was 14.7%. On the other hand, the rate of falls in patients at SIDE level ≧ 2b was 2.9%. Gender was the variable for the second classification. In this analysis, drugs weren't identified as divergence variables for falls. CONCLUSION: The SIDE balance assessment was the initial divergence variable by decision tree analysis. In order to prevent falls, it seems important not only to select appropriate hypnotic drugs but also to assess patients for balance and implement preventive measures.

Electrically stimulated eccentric contraction during non-weight bearing knee bending exercise in the supine position increases oxygen uptake: A randomized, controlled, exploratory crossover trial.

It is well known that prolonged bed rest induces muscle weakness, muscle atrophy, cardiovascular deconditioning, bone loss, a loss of functional capacity, and the development of insulin resistance. Neuromuscular electrical stimulation is anticipated to be an interventional strategy for disuse due to bed rest. A hybrid training system (HTS), synchronized neuromuscular electrical stimulation for voluntary exercise using an articular motion sensor, may increase the exercise load though bed rest. We assessed oxygen uptake or heart rate during knee bending exercise in the supine position on a bed both simultaneously combined with HTS and without HTS to evaluate exercise intensity on different days in ten healthy subjects (8 men and 2 women) by a randomized controlled crossover trial. The values of relative oxygen uptake during knee bending exercise with HTS were significantly greater than those during knee bending exercise without HTS (7.29 ± 0.91 ml/kg/min vs. 8.29 ± 1.06 ml/kg/min; p = 0.0115). That increment with HTS was a mean of 14.42 ± 13.99%. Metabolic equivalents during knee bending exercise with HTS and without HTS were 2.08 ± 0.26 and 2.39 ± 0.30, respectively. The values of heart rate during knee bending exercise with HTS were significantly greater than those during knee bending exercise without HTS (80.82 ± 9.19 bpm vs. 86.36 ± 5.50 bpm; p = 0.0153). HTS could increase exercise load during knee bending exercise which is easy to implement on a bed. HTS might be a useful technique as a countermeasure against the disuse due to bed rest, for example during acute care or the quarantine for infection prophylaxis.

Electrically Stimulated Eccentric Contractions during Walking Increases Oxygen Uptake.

Neuromuscular electrical stimulation (NMES) is used to increase not only muscle strength but also whole-body metabolism. A hybrid training system (HTS) in which NMES is synchronized to voluntary exercise by an articular motion sensor may increase exercise load during aerobic walking exercise. We assessed the metabolic cost during walking exercise (5 minutes at 4 km/h and 5.6 km/h) on a treadmill simultaneously combined with HTS (HTSW) or without HTS (CON). We evaluated oxygen uptake ( VO·2) and heart rate (HR) during HTSW or CON on different days in fifteen subjects. The values ofVO·2 during HTSW at 4 km/h and 5.6 km/h were signifi cantly greater than those during CON (16.6 ± 1.85 ml/min/kg vs 15.3 ± 1.48 ml/min/kg; p < 0.05, 21.0 ± 2.17 ml/min/kg vs 19.4 ± 2.13 ml/min/kg; p < 0.01, respectively). The values of HR during HTSW at 4 km/h, 5.6 km/h were significantly greater than those during CON (106.7 ± 8.1 bpm vs 101.7 ± 10.3 bpm; p < 0.05, 126.5 ± 11.1 bpm vs 121.5 ± 12.5 bpm; p < 0.05, respectively). HTS added significantly to the exercise load by 8.3 ± 12.0% or 9.1 ± 9.9% during aerobic walking exercise at 4 km/h or 5.6 km/h, respectively. HTS might be useful for health promotion by increasing metabolic cost during aerobic walking exercise without increasing the perceived difficulty.

Electrical Stimulation of the Antagonist Muscle During Cycling Exercise Interval Training Improves Oxygen Uptake and Muscle Strength.

ABSTRACT: Hashida, R, Takano, Y, Matsuse, H, Kudo, M, Bekki, M, Omoto, M, Nago, T, Kawaguchi, T, Torimura, T, and Shiba, N. Electrical stimulation of the antagonist muscle during cycling exercise interval training improves oxygen uptake and muscle strength. J Strength Cond Res 35(1): 111-117, 2021-A hybrid training system (HTS) is a resistance exercise method that combines voluntary concentric muscle contractions and electrically stimulated eccentric muscle contractions. We devised an exercise technique using HTS on cycle ergometer (HCE). The purpose of this study was to compare cardiorespiratory function and muscle strength when cycling exercise is combined with electrical stimulation over an extended period. Twenty-nine healthy young men were divided into an HCE group (n = 14) and a volitional cycle ergometer (VCE alone) group (n = 15). All subjects performed 30-minute cycling exercise interval training sessions 3 times a week for 6 weeks. The V̇o2peak of both groups significantly increased compared with the pretraining period (HCE group: from 31.3 ± 4.4 [ml·kg-1·min-1] pretraining to 37.6 ± 6.7 [ml·kg-1·min-1] post-training [p = 0.0024] and VCE group: from 34.0 ± 7.1 [ml·kg-1·min-1] pretraining to 38.4 ± 8.2 [ml·kg-1·min-1] [p = 0.0057]). After the training, there was no significant difference of changes in V̇o2peak between the HCE and the VCE groups (p = 0.7107). In the VCE group, the maximal isokinetic torque of knee extension (60°·s-1) post-training did not significantly increase compared with the pretraining period (VCE group: from 2.4 ± 0.5 [N·m·kg-1] pretraining to 2.5 ± 0.4 [N·m·kg-1] [p = 0.4543]). By contrast, in the HCE group, the maximal isokinetic torque of knee extension (60°·s-1) post-training significantly increased compared with pretraining period (HCE group: from 2.5 ± 0.3 [N·m·kg-1] pretraining to 2.8 ± 0.3 [N·m·kg-1] [p < 0.0001]). The change in knee extension torque was significantly greater for the HCE group than for the VCE group (p = 0.0307). In conclusion, cardiopulmonary function and knee extension strength were improved by the use of HCE.

Hybrid Training System Improves Insulin Resistance in Patients with Nonalcoholic Fatty Liver Disease: A Randomized Controlled Pilot Study.

Insulin resistance is associated with the progression of nonalcoholic fatty liver disease (NAFLD). Insulin resistance is regulated by various cytokines, including interleukin-6 (IL-6), a proinflammatory myokine, and selenoprotein P (SeP), a liver-derived secretory hepatokine. High levels of IL-6 and/or SeP have been shown to contribute to insulin resistance, and exercise is a first-line therapy for NAFLD. We have developed a hybrid training system (HTS): a neuromuscular electrical stimulation device to enhance exercise results. We aimed to investigate the effects of HTS on insulin resistance as well as serum IL-6 and SeP in patients with NAFLD. This is a randomized, single-blind (assessor), controlled trial. Subjects with NAFLD walked on a treadmill with or without HTS (9 subjects each) for 30 minutes three times a week for six weeks (HTS vs. control group; median age 45 vs. 45; male/female 5/4 vs. 6/3). We examined subjects before the first session and at the end of the final session. Serum SeP levels were measured by ELISA which measures the fragment of SeP. In the HTS group, HOMA-IR values were significantly reduced compared to the control group (Δ-0.71 vs. Δ0.05; P < 0.05). IL-6 and SeP levels in serum were also significantly reduced compared to that of the control group (IL-6; Δ-0.6 vs. Δ0.29 pg/mL; P < 0.05, SeP; Δ-1288.5 vs. Δ-435.4 ng/mL; P < 0.05, respectively). In conclusion, we propose that HTS improves insulin resistance by reducing serum IL-6 and SeP levels in patients with NAFLD.

Combined Application of Electrically Stimulated Antagonist Muscle Contraction and Volitional Muscle Contraction Prevents Muscle Strength Weakness and Promotes Physical Function Recovery After Total Knee Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: Osteoarthritis of the knee (KOA) is the most common cause of disability in both the United States and in Japan. The Hybrid training system (HTS) has been developed as a resistance exercise method combining electrical stimulation with voluntary exercise. The purpose of the present study is to compare the effects of a conventional rehabilitation program with or without HTS on knee muscle strength and physical function after Total knee arthroplasty (TKA). METHODS: We conducted a 12-week randomized controlled trial, using standard rehabilitation (the control group, n = 27) or standard rehabilitation plus HTS (the HTS group, n= 26), in 53 female patients after TKA. The HTS group underwent HTS three times per week for twelve weeks after TKA. Muscle strength, thigh circumference, physical functional testing, QOL and knee pain were assessed before surgery, 6 and 12 weeks after TKA. RESULTS: There was a significant decrease in quadriceps strength and thigh circumference on the operative side in the control group, but not in the HTS group at 6 weeks. Hamstring strength on the operative side in the HTS group significantly increased and thigh circumference was bigger than in the control group at 12 weeks. Physical function improved at 6 weeks in the HTS group, but not in the control group. Knee pain significantly improved in both groups at 6 weeks. CONCLUSIONS: HTS was effective in preventing quadriceps weakness and in improving physical function and QOL after TKA.

Evaluation of Motor-Assisted Gloves (SEM Glove) for Patients with Functional Finger Disorders: A Clinical Pilot Study.

The SEM Glove developed by Bioservo Technologies AB is a new device that increases grip and pinch force. The purpose of this study was to evaluate the effectiveness of the device on the grip and pinch strength of patients with functional disorders of the fingers. MATERIALS AND METHOD: 30 hospitalized patients with upper limb functional disorder were enrolled. The assistance of the device for the grip and pinch strength of each subject were assessed by the difference between the measured values with and without the SEM Glove. The 95% confidence interval of the difference was calculated across the subjects, and statistical significance was defined as when the lower limit was a positive value (corresponding with a paired t-test at a significance level of 0.05). The odds ratio was calculated in the study of subject adaptation, with statistical significance set using Fisher's exact test at a significance level of 0.05. RESULTS: Grip strength significantly decreased (worn-not worn difference (kg): mean = -3.7, CI95 (-5.4, -2.1)). Pinch strength (thumb - middle finger) significantly increased (worn-not worn difference (N): mean = -4.1, CI95 (1.6, 6.6)). Analysis of factors related to improvement in hand function when wearing the SEM Glove extracted manual muscle tests (MMTs) of the upper extremity 4 or higher. The odds ratio was 6.11. CONCLUSIONS: Use of the SEM Glove improved the pinch strength of patients with functional disorders of the hands.

Walking Exercise Simultaneously Combined With Neuromuscular Electrical Stimulation of Antagonists Resistance Improved Muscle Strength, Physical Function, and Knee Pain in Symptomatic Knee Osteoarthritis: A Single-Arm Study.

Matsuse, H, Hashida, R, Takano, Y, Omoto, M, Nago, T, Bekki, M, and Shiba, N. Walking exercise simultaneously combined with neuromuscular electrical stimulation of antagonists resistance improved muscle strength, physical function, and knee pain in symptomatic knee osteoarthritis: a single-arm study. J Strength Cond Res 31(1): 171-180, 2017-A hybrid training system (HTS) was developed as a way to combine the application of electrical stimulation and voluntary contraction. Moreover, we developed a novel training method using HTS during walking (HTSW). This study was designed to evaluate the effect of HTSW on muscle strength, physical function, and knee pain in knee osteoarthritis (KOA). Eleven subjects (age: 74.0 ± 8.5 years) participated and performed HTSW for 30 minutes 3 times a week for 12 weeks. Isokinetic knee extension/knee flexion torque, muscle volume, one-leg standing test (OST), functional reach test, 10-m maximum gait speed, timed up and go test, 6-minute walking test, knee pain using Visual Analog Scale (VAS), and Japan Knee Osteoarthritis Measure (JKOM) were assessed. Knee extension torque significantly increased from 1.02 ± 0.29 N·m·kg pretraining to 1.23 ± 0.33 N·m·kg posttraining (P < 0.01, ES = 0.68). Knee flexion torque significantly increased from 0.65 ± 0.18 N·m·kg pretraining to 0.78 ± 0.17 N·m·kg posttraining (p < 0.01). Muscle volume significantly increased from 9.00 ± 2.84 mm pretraining to 10.37 ± 3.16 mm at the end of training (p ≤ 0.05). All the physical functions except OST were significantly improved. The JKOM score improved from 26.7 ± 18.30 pretraining to 17.2 ± 14.02 at the end of training (p < 0.01). The VAS score significantly decreased from 35.4 ± 22.59 pretraining to 16.5 ± 19.73 at the end of training (p ≤ 0.05). Hybrid training system during walking may be an effective training method for the treatment of people with KOA.

Aerobic vs. resistance exercise in non-alcoholic fatty liver disease: A systematic review.

BACKGROUND & AIMS: Exercise is a first-line therapy for patients with non-alcoholic fatty liver disease (NAFLD). We sought to: 1) summarize effective aerobic and resistance exercise protocols for NAFLD; and 2) compare the effects and energy consumption of aerobic and resistance exercises. METHODS: A literature search was performed using PubMed, Web of Science, and Scopas to January 28, 2016. From a total of 95 articles, 23 studies including 24 aerobic and 7 resistance exercise protocols were selected for the summary of exercise protocols. Twelve articles including 13 aerobic and 4 resistance exercise protocols were selected for the comparative analysis. RESULTS: For aerobic exercise, the median effective protocol was 4.8 metabolic equivalents (METs) for 40min/session, 3times/week for 12weeks. For resistance exercise, the median effective protocol was 3.5 METs for 45min/session, 3times/week for 12weeks. Aerobic and resistance exercise improved hepatic steatosis. No significant difference was seen in the duration, frequency, or period of exercise between the two exercise groups; however, %VO2max and energy consumption were significantly lower in the resistance than in the aerobic group (50% [45-98] vs. 28% [28-28], p=0.0034; 11,064 [6394-21,087] vs. 6470 [4104-12,310] kcal/total period, p=0.0475). CONCLUSIONS: Resistance exercise improves NAFLD with less energy consumption. Thus, resistance exercise may be more feasible than aerobic exercise for NAFLD patients with poor cardiorespiratory fitness or for those who cannot tolerate or participate in aerobic exercise. These data may indicate a possible link between resistance exercise and lipid metabolism in the liver. LAY SUMMARY: Both aerobic and resistance exercise reduce hepatic steatosis in non-alcoholic fatty liver disease (NAFLD) with similar frequency, duration, and period of exercise (40-45min/session 3times/week for 12weeks); however, the two forms of exercise have different characteristics. Intensity and energy consumption were significantly lower for resistance than for aerobic exercise. Resistance exercise may be more feasible than aerobic exercise for NAFLD patients with poor cardiorespiratory fitness or for those who cannot tolerate or participate in aerobic exercise.

[Space flight/bedrest immobilization and bone. Development a devise to maintain the skeletal muscles in space].

We have developed a "hybrid training system" (HTS) that is designed to maintain the musculoskeletal system of astronauts by using an electrically stimulated antagonist to resist the volitional contraction of agonist muscles in weightlessness. In other words, electrical stimulation generates a resistive force instead of gravity. HTS will become a useful back-up for the standard training device in the International Space Station, or a useful training device in the small space ship for the exploration of the Moon and Mars.

Hybrid-training method increases muscle strength and mass in the forearm without adverse effect of hand function in healthy male subjects.

Conventional neuromuscular electrical stimulation (NMES) results in surface muscle contraction but high electrical stimulation intensity is required to activate the deep muscles. Therefore, NMES is not useful for training at complicated sites such as the forearm. To make NMES more effective we developed a hybrid training method (HYB), consisting of electrically stimulated antagonists to resist agonist muscle contractions. The purpose of this study was to compare the effects of HYB on the forearm as compared with NMES alone, and to determine whether HYB had any adverse effects on complex hand movements. Thirty subjects were randomly distributed into three groups: a HYB program group, an isometric electrical stimulation group (ES), and a control group (CN). Subjects trained 3 times a week for 6 weeks. Each session consisted of 10 sets of 10 reciprocal 2-sec wrist flexions and extensions separated by 1-min rest intervals. Wrist flexion/extension torques, grip strengths (GS), forearm flexor/extensor cross sectional areas (CSA), and hand dexterity (Purdue Pegboard (PEG) test, finger tapping (Tapping) test were measured. The HYB group demonstrated statistically significant increases in wrist extension torques (22.8%, p<0.01), forearm flexor CSA (9.6%, p<0.01), and in forearm extensor CSA (5.1%, p<0.05) at the end of training. There was no increase in torque or CSA in the ES or CN groups. Hand dexterity showed no significant differences in any of the three groups. HYB had no adverse effect on hand function and was more effective in forearm training than NMES alone.

Plasma growth hormone is elevated immediately after resistance exercise with electrical stimulation and voluntary muscle contraction.

Resistance exercise is a physiological stimulus for acute increases in growth hormone (GH) secretion, and it also causes lactate accumulation and stimulates norepinephrine (NE) secretion as a sympathetic nervous response. The hybrid exercise method (HYB) is a novel resistance exercise method that combines a voluntary concentric muscle contraction and an electrically stimulated eccentric muscle contraction. This study was designed to compare the hormonal responses of HYB with typical weight training (WT), as regards GH, lactate, and NE. Twenty-four healthy male subjects (20-27 years) were divided into the HYB group and the WT group. All the subjects performed bilateral leg exercises with 10 sets of 10 reciprocal 2-second (45 degrees /sec) knee flexion-and-extension contractions, and with 1-min interset rest intervals. Plasma concentrations of GH, lactate, and NE were determined before exercise and immediately after exercise (0 min) as well as at 15, 30, 60, and 120 min. The plasma concentrations of GH and lactate were significantly increased immediately after HYB or WT (P < 0.05). Moreover, the degree of the increases of GH and lactate after HYB was significantly higher than that after WT (P < 0.05). The plasma concentration of NE was significantly increased after HYB or WT (P < 0.01), but no significant difference was observed between the two groups. These results indicate that HYB is more efficient in stimulating acute increases in plasma GH and lactate without enhancing sympathetic nerve stimulation, compared to WT. Therefore, HYB may be an effective countermeasure to muscle disuse associated with bed rest or spaceflight.

Muscle maintenance by volitional contraction against applied electrical stimulation.

Muscle training exercises are needed for muscular endurance during spaceflight. This study was designed to investigate effects of volitional contraction against applied electrical stimulation on the muscular endurance of the proximal upper extremity. Thirteen healthy sedentary men were allocated into two groups. One group participated in a hybrid (HYB) exercise regimen in which the biceps brachii was stimulated as he volitionally extended his elbow, and the triceps brachii was stimulated as the volitionally flexed his elbow. The second group underwent a similar regimen in which the electrical stimulation (ELS) was alternatively delivered to the biceps brachii and then to the triceps brachii with the limb fixed. Forty-second surface electromyography (EMG) recordings at 50% maximum voluntary contraction (MVC) were made as baseline data at just before starting the training regimen, and again conclusion. The median frequency (MF) and mean power frequency (MPF) slopes with time were determined using power spectrum analysis. There were statistical significance only for the triceps in which the MF and MPF slopes in the HYB Group became less negative over the period of study (from -45.7+/-14.7 and -47.0+/-8.6%/min at baseline to -36.9+/-10.7 and -36.8+/-7.0%/min at the end of training, respectively). The corresponding values for these slopes in the ELS Group showed opposite tends with less marked changes of borderline significance for MF and of statistical significance for MPF. These results suggested that the HYB exercise regimen was capable of producing an improvement in triceps but not biceps brachii.

Improvement in knee extension strength through training by means of combined electrical stimulation and voluntary muscle contraction.

Weight training (WT) is the most common method of maintaining and increasing muscle strength. WT, however, is not always useful as it requires the external resistance and stabilization. We have developed a "hybrid training" (HYB) approach that avoids these problems by using electrically stimulated muscles to provide resistance to the motion of a muscle undergoing training. Here we report the efficacy of HYB compared with conventional WT for increasing the muscle strength around the knee at both slow and fast joint speeds (at 30 and 180 degrees /sec). Two matched groups, each of 8 healthy men aged 22 years, exercised 3 times/week for six weeks. Both groups showed significantly increased strength in concentric torque at 30 degrees /sec (HYB +28%, WT +33%) and at 180 degrees /sec (HYB +33%, WT +38%), and also in eccentric torque at 30 degrees /sec (HYB +25%, WT +24%) and at 180 degrees /sec (HYB +19%, WT +30%) (p < 0.001). HYB is comparable with WT exercising with the exception of high-speed contractions, while HYB has a clear advantage in not needing external resistance equipment or stabilization. HYB is therefore considered a useful approach for strengthening muscles when a person is restricted to bed rest or during space flight.

Effects of a hybrid exercise on the activities of myogenic enzymes in plasma.

"Hybrid" exercise uses forces generated by an electrically stimulated muscle to resist the motion of a volitionally contracting agonist. This approach is effective in increasing muscle bulk and strength. Its safety, however, has not been studied and the purpose of this study was to address this lack by assessing the impact of a hybrid strengthening regimen on the serological markers of exercise associated muscle damage. Twelve healthy, sedentary men between the ages of 20 and 27 years were divided into two groups of 6. The members of each group completed an exercise session that consisted of 10 sets of 10 reciprocal elbow flexor and extensor contractions separated by 1-minute rest intervals. In one group, the subjects underwent a hybrid exercise protocol. Subjects in the second group underwent a conventional isometric electrical stimulation program with the same stimulation intensities. Plasma creatine kinase (CK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) activities were determined immediately before and after the exercise session as well as at follow-up 1, 2, and 7 days later. Secondary variables included active and passive range of motion and the subjects' perceived levels of "soreness" . Evaluation revealed that neither enzymatic activities nor range of motion changed in a statistically significant manner with time within the groups or between the groups. In conclusion, the stimulation intensities involved in hybrid exercise programs of the upper extremity do not appear to be associated with either overt or covert signs of muscle injury.