Mechanomyographic and electromyographic amplitude and frequency responses from the superficial quadriceps femoris muscles during maximal, eccentric isokinetic muscle actions.

The purposes of this study were to examine the effects of gender and muscle (vastus lateralis = VL, rectus femoris = RF, and vastus medialis = VM) on the velocity-related patterns for peak torque (PT), mean power output (MP), mechanomyographic (MMG) amplitude, electromyographic (EMG) amplitude, MMG mean power frequency (MPF), and EMG MPF during maximal, eccentric isokinetic muscle actions. Thirteen females (mean +/- SD age = 21 +/- 1 years) and eleven males (mean +/- SD age = 21 +/- 2 years) volunteered for this investigation. PT and MP were measured on a calibrated Cybex 6000 dynamometer at randomly ordered velocities of 60, 120, and 180 degrees.s-1, while MMG and EMG signals were recorded simultaneously from the VL, RF, and VM muscles. The results indicated no gender-related differences for the patterns of PT, MP, MMG amplitude, EMG amplitude, MMG MPF, or EMG MPF. Furthermore, no muscle-related differences were found for the patterns of MMG amplitude, EMG amplitude, or MMG MPF. The normalized values for MP and MMG amplitude increased from 60 to 180 degrees.s-1 (60 degrees.s-1 < 120 degrees.s-1 < 180 degrees.s-1). PT and EMG MPF remained unchanged across velocity, while EMG amplitude remained unchanged from 60 to 120 degrees.s-1, but decreased (approximately 10%) from 120 to 180 degrees.s-1. The findings indicated a close association between the patterns for MP and MMG amplitude, and a similarity between the patterns for PT, EMG amplitude, and EMG MPF across velocity. Therefore, the present findings suggested that motor unit recruitment (EMG amplitude), firing rate (MMG MPF), and muscle fiber action potential conduction velocity (EMG MPF) exhibited velocity-related patterns that were similar to PT production, while MMG amplitude was more closely associated with MP.

Development of a branching submaximal treadmill test for predicting VO2max.

This study determined the reliability and validity of a branching treadmill protocol in predicting VO2max. Thirty-seven, apparently healthy individuals (19 women and 18 men); volunteered to participate. On 2 separate testing days, each subject underwent maximal exercise testing using the protocol developed. Stepwise regression analysis indicated that the percentage of age-predicted maximum heart rate (APMHR) achieved at stage 3, speed and grade at stage 3, and APMHR accounted for 89% of the variance in VO2max. The 4 predictor variables were statistically significant (p < 0.01), and the standard error of the estimate was 4.56 ml x kg(-1) min(-1). Results indicate that health and fitness professionals can incorporate this protocol into their practices for the purpose of predicting VO2max for their clients outside the laboratory environment. Furthermore, our results indicate that using the proposed regression model is reliable and has received preliminary construct validity support.

Progressive strength training in sedentary, older African American women.

PURPOSE: This study investigated effects of an 8-wk, low-frequency and low-volume, supervised, progressive strength training program emphasizing free weight, multijoint movements on the muscular power, strength, endurance, and flexibility of African American women 44 to 68 yr of age. METHODS: Nineteen sedentary African American women were randomly assigned to a strength training (ST) only group (N = 12; mean age, 51 yr) or a nonexercise control (C) group (N = 7; mean age, 52 yr). Maximal power, strength, absolute endurance, and flexibility were assessed before and after training. Subjects trained 2 d x wk(-1) using free weight (barbells and dumbbells) and machine (plate loaded) exercises for two to three sets of 8 to 10 repetitions on both primary and assistance exercises. RESULTS: Upper body power (medicine ball put distance) significantly increased statistically (P = 0.002), but gains possibly lacked practical significance because of measurement variation. Lower body power (peak watts on bicycle) experienced a small, nonsignificant increase in the ST group. Significant increases (P = 0.000) in 1RM muscle strength occurred in the ST group (leg press, +99.8%; bench press, +34.4%). Absolute endurance significantly increased (P = 0.000) in the ST group (leg press repetitions to failure at 70% pretest 1RM, +221%; bench press repetitions to failure at 50% pretest 1RM, +112%). Significant flexibility gains occurred in the ST group (sit-and-reach test, +8.2%; P = 0.017). No significant changes occurred in power, strength, absolute endurance, or flexibility in the C group. CONCLUSION: This study demonstrates that 8 wk of low-frequency, supervised, progressive strength training emphasizing free weight, multijoint movements can safely cause significant gains in muscle strength, absolute endurance, and flexibility in older African American women.

Cardiopulmonary responses, muscle soreness, and injury during the one repetition maximum assessment in pulmonary rehabilitation patients.

PURPOSE: The safety of one repetition maximum (1RM) testing for patients with chronic obstructive pulmonary disease (COPD) has not been determined. Therefore, this study was conducted to determine the prevalence of abnormal cardiopulmonary responses, muscle soreness, and muscle injury of patients with moderate to severe COPD in response to 1RM testing. METHODS: Twenty pulmonary rehabilitation patients (11 women and 9 men) with moderate or severe COPD participated in this investigation. The 1RM testing was performed using the parallel squat and incline press. Blood pressure, heart rate dyspnea ratings, and oxygen saturation responses were measured immediately following the 1RM procedure. Ratings of muscle soreness and injury were measured immediately after 1RM testing and on days 2 and 7. RESULTS: No injury, significant muscle soreness, or abnormal cardiopulmonary responses occurred as a result of 1RM testing. No gender differences were found for any variable measured in response to 1RM testing. CONCLUSIONS: A properly supervised and screened pulmonary rehabilitation population can be 1RM tested without significant muscle soreness, injury, or abnormal cardiopulmonary responses.