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Examines the effect of Siberian Ginseng on fat utilization and performance during prolonged cycling. Role of ginseng in preventing glycogen depletion; Materials and methology used in the study; Approach used in the analysis of data.

The article reports on research which was conducted to investigate the effects postactivation potentiation (PAP) had on vertical and horizontal jump performance, shot put performance and sprint performance in National Collegiate Athletic Association Division II athletes. Researchers evaluated 12 male and eight female athletes. They found that PAP enhanced both upper and lower body athletic performance in male and female athletes.

Purpose: Obesity may attenuate metabolic health improvements following lifestyle interventions. However, the effect of adiposity on insulin action following resistance exercise in young non-diabetic women is unknown. The purpose of this study was to test the hypothesis that adiposity attenuates improvements in insulin sensitivity and glucose-stimulated insulin secretion (INS 0–60/GLC 0–60) after both acute resistance exercise (ARE) and progressive training (PRT). Methods: Twenty-six young non-diabetic women (21.2 ± 0.7 years) were randomly assigned to control (C; n = 7; BF 40.1 ± 2.1 %) or exercise groups: normal body fat (NBF; n = 8; BF 29.9 ± 2.3 %) and high body fat (HBF; n = 12; BF 48.2 ± 1.4 %). Acute whole-body exercises were performed at 60 % of 1-RM for three sets of 8–12 repetitions, and PRT was performed 3 days/week for 7 weeks. A 75 g OGTT was conducted before and after ARE and PRT to estimate insulin sensitivity (Matsuda index) and INS 0–60/GLC 0–60. Insulin area under the curve (AUC) was calculated using the trapezoidal model. Results: ARE had no statistical effect on insulin action across groups. Strength and fat-free mass (via DXA) increased after PRT in both NBF and HBF ( p < 0.05), but only HBF women decreased BF ( p < 0.01). HBF women were less insulin sensitive at baseline compared to NBF women ( p < 0.05). Insulin sensitivity increased 95 % and INS 0–60/GLC 0–60 decreased 32 % following PRT in NBF, but not HBF or C ( p < 0.05). After training, enhanced insulin sensitivity was inversely related to decreased INS 0–60/GLC 0–60 ( r = −0.71, p < 0.001), fasting insulin ( r = −0.71, p < 0.001), and insulin AUC ( r = −0.85, p < 0.001). Conclusion: Seven weeks of PRT increases insulin sensitivity and reduces glucose-stimulated insulin secretion in NBF, but not HBF women. Obesity attenuates exercise-induced improvements in glucose regulation in young non-diabetic women. [ABSTRACT FROM AUTHOR]

The article presents the results of a study which analyzed data about the effects of acute static stretching on females, in terms of torque and electromyography. An overview of related previous research is provided, along with details of the experimental protocol. Normalized and non-normalized data from both athletes and non-athletes was studied.

The article reports on research conducted to determine the effects acute low- and high-volume static and proprioceptive neuromuscular facilitation (PNF) stretching had on athletes who performed a one-repetition maximum bench press. Researchers evaluated 15 college football players. They found that there were no significant differences in bench press performance in athletes who participated in either type of stretching.

The purpose of the study was to examine the potential for using the mechanomyographic (MMG) signal as a biofeedback method to enhance muscular relaxation and to improve performance during forearm flexion repetitions to fatigue. Twelve adult (mean ± SD; age: 22.0 ± 1.1 years) moderately trained subjects (weight: 82.3 ± 29.2 kg; height: 165.7 ± 49.0 cm) were instructed to relax the biceps brachii muscle using MMG biofeedback (BIO) provided by viewing a computer screen graphically displaying the MMG signal and then without using MMG biofeedback (NOBIO). Electromyographic (EMG) and MMG signals were detected midway over the biceps brachii during the relaxation protocol. In subsequent visits to the laboratory, subjects performed as many repetitions as possible at 85% of 1 repetition maximum with BIO and NOBIO using the seated preacher curl exercise. Two-way (biofeedback × gender) mixed factorial analyses of variance revealed significantly (p < 0.05) lower MMG (mean ± SEM; BIO = 0.6 ± 0.1 mV; NOBIO = 1.1 ± 0.2 mV) and EMG amplitudes (BIO = 6.6 ± 0.6 μV; NOBIO = 9.4 ± 1.4 μV) for BIO when subjects were instructed to relax the biceps brachii muscle. There was no significant difference in the number of forearm flexion repetitions performed for BIO (mean ± SD; 7.9 ± 0.4 reps) vs. NOBIO (8.1 ± 0.6 reps). The results of the present study revealed that using MMG as a biofeedback technique can enhance the development of muscle relaxation, but is not useful in delaying fatigue during forearm flexion repetitions. Our results may have been influenced by a relatively short training phase designed to teach subjects to use the MMG signal as a biofeedback method. Future studies are needed to determine whether MMG biofeedback can be used for other purposes. If MMG is found to be useful as a biofeedback method, it has some distinct practical advantages over EMG that the strength and conditioning athlete and professional may find appealing. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to determine the effect of hyperhydration on the electromyographic (EMG) and mechanomyographic (MMG) responses during isometric and isokinetic muscle actions of the biceps brachii. Eight (22.1 ± 1.8 years, 79.5 ± 22.8 kg) subjects were tested for maximal isometric, submaximal isometric, and maximal concentric isokinetic muscle strength in either a control (C) or hyperhydrated (H) state induced by glycerol ingestion while the EMG and MMG signals were recorded. Although fluid retention was significantly greater during the H protocol, the analyses indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, or MMG MPF with hyper-hydration. These results indicated that glycerol-induced fluid retention does not affect the torque-producing capabilities of a muscle, the impulses (EMG) going to a muscle, or muscular vibrations (MMG). It has been suggested that EMG and MMG can be used as direct electrical/mechanical monitoring, which could be presented to trainers and athletes; however, before determining the utility of these signals, the MMG and EMG responses should be examined under a variety of conditions such as in the present study. [ABSTRACT FROM AUTHOR]

The purpose of the present investigation was to examine the velocity-related patterns of peak torque (PT), mean power output (MP), mechanomyographic (MMG) amplitude, and electromyographic (EMG) amplitude of the vastus lateralis (VL) muscle in men and women during maximal, eccentric isokinetic muscle actions of the leg extensors. Eight women [mean (SD)] [aged 23 (3) years] and seven men [aged 23 (2) years] volunteered for this investigation. Their PT was measured on a calibrated dynamometer at randomly ordered velocities of 30, 90, and 150 degrees x s(-1). A piezoelectric MMG recording sensor was placed between bipolar surface EMG electrodes (Ag-AgCl) over the VL muscle. Their MP was determined using the dynamometer software. The results indicated no sex-related differences (P > 0.05) for the patterns of PT, MP, MMG amplitude, or EMG amplitude across velocity. The normalized values for MP and MMG amplitude increased (P<0.05) from 30 to 150 degrees x s(-1) (30 degrees x s(-1) <90 degrees x s(-1) < 150 degrees x s(-1)), while PT and EMG amplitudes remained unchanged across velocity. The results indicated close associations between the velocity-related patterns of MP and MMG amplitudes as well as PT and EMG amplitudes. Thus, MMG amplitude reflected the velocity-related changes in muscle power output, but not torque production, while EMG amplitude reflected torque production, but not muscle power output. During maximal, eccentric isokinetic muscle actions, EMG and MMG signals provided unique information regarding the electrical and mechanical aspects of muscle strength and power. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to examine the mechanomyographic (MMG) responses to maximal concentric (CON) and passive leg extension movements. Eight adult females performed maximal CON muscle actions and passive leg extension movements of the dominant leg on a calibrated CYBEX 6000 dynamometer at velocities of 30, 90, and 150 [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to examine the effect of leg flexion angle on the relationship between mechanomyographic (MMG) amplitude and isometric torque production. Adult males ( n = 9) performed isometric muscle actions of the leg extensors at 25, 50, 75, and 100 percent maximal voluntary contraction (%MVC) on a calibrated CYBEX 6000 dynamometer at 25, 50, and 75° below full extension. A piezoelectric MMG recording device was placed over the mid-portion of the rectus femoris. At 25° of leg flexion, the MMG amplitude increased to 100%MVC. At 50 and 75° of leg flexion, however, MMG amplitude increased to 75%MVC, and then did not change significantly ( P > 0.05) between 75 and 100%MVC. These findings indicate that the MMG amplitude-isometric torque relationship is joint angle specific and may be the result of leg flexion angle differences in: (1) muscle stiffness, or (2) motor unit activation strategies. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to describe and compare the relationships for mechanomyography (MMG) and oxygen consumption rate ( V˙O2) versus power output during incremental cycle ergometry. Twenty four adult males [mean (SD) age, 22.1 (2.0) years] volunteered to perform an incremental test to exhaustion on a cycle ergometer. A MMG piezoelectric recording device was placed mid-thigh over the vastus lateralis muscle and V˙O2 was measured using standard open circuit procedures. The r2 values for the MMG and V˙O2 versus power output relationships ranged from 0.79 to 0.99 and 0.97 to 0.99, respectively. In 20 of the 24 subjects there was no significant ( P > 0.10) difference between the slope values for the normalized MMG and V˙O2 (expressed as a percentage of maximal values) versus power output relationships. The results of this study indicate that MMG procedures can be used to quantify muscular activity and monitor changes in exercise intensity during cycle ergometry. Furthermore, the present findings demonstrated a close association between the mechanical (MMG) and metabolic ( V˙O2) aspects of muscular contraction during incremental cycle ergometry. [ABSTRACT FROM AUTHOR]

The purpose of this investigation was to examine the effects of velocity of contraction on the mechanomyographic (MMG) responses to maximal concentric isokinetic leg extension movements. Eight adult males [mean (SD) age, 22.3 (1.3) years] performed maximal leg extensions on a calibrated Cybex 6000 dynamometer at velocities of 60, 120, 180, 240, 300, and 360° · s−1. MMG responses were detected by a piezoelectric recording device placed over the vastus lateralis muscle. Intraclass reliability correlations ranged from R = 0.84 to 0.97 and from 0.90 to 0.99 for peak torque and MMG amplitude values, respectively, with no significant differences ( P > 0.05) between the mean values for test versus retest at any contraction velocity. There were significant differences ( P < 0.05) in peak torque at all velocities except 240 [135 (27) Nm] versus 300 [127 (27) Nm], and 300 versus 360° · s−1 [115 (37) Nm]. The mean MMG amplitude at 60° · s−1 [61 (67) mV] was significantly less ( P < 0.05) than that at 360° · s−1 [452 (451) mV]. These results indicate a velocity-related dissociation between MMG amplitude and peak torque. Furthermore, it was hypothesized that the increases in MMG amplitude were due to velocity-related decreases in muscle stiffness which allowed for greater muscle fiber oscillations. [ABSTRACT FROM AUTHOR]

The purpose of the present investigation was to examine the effect of concentric isokinetic leg extension training on peak torque (PT) and mechanomyographic (MMG) responses. Twenty-one males were assigned into a training (TRN, n=12) or control (CTL, n=9) group. The training group performed six sets of ten leg extensions three days per week for twelve weeks at a velocity of 90\dgs. All subjects were tested every four weeks for PT and MMG responses at a velocity of 90 dgs. The two-way mixed factorial ANOVA indicated a significant increase (p < 0.05) in PT over the twelve weeks for the TRN group but no significant change (p>0.05) in PT for the CTL group. For the MMG there was no significant (p>0.05) interaction, therefore, the TRN and CTL groups exhibited the same pattern of responses over the twelve-week training period. The reason for the increase in PT in the absence of a change in MMG may be due to hypertrophy and/or changes in other muscles involved in leg extension. [ABSTRACT FROM AUTHOR]

The purpose of this study was twofold: (1) to determine the effect of increasing the duration of the workbout at each power output during the physical working capacity at fatigue threshold (PWC FT) test from 2 to 3 or 4 min, and (2) to examine the time to exhaustion during continuous workbouts at the PWC FT. Twelve adult males (χ¯± SD = 22.4 ± 3.0 years) volunteered to perform three PWC FT tests using workbout durations of 2, 3, and 4 min. Following the determination of the PWC FT values, nine of the subjects performed continuous workbouts at PWC FT2 and PWC FT4 for as long as possible. The mean PWC FT value using 4-min workbouts (PWC FT4 = 168.8 ± 45.1 W) was significantly less (p<0.05, 19 1%) than that using 2-min workbouts (PWC FT2 = 208.9 ± 59.0W). However, only two subjects were able to complete 60 min at PWC FT4 and none of the subjects were able to complete 60min at PWC FT2. Therefore, although increasing the duration of the workbout at each power output resulted in a lower PWC FT4, these findings do not support a recommendation for a change in the PWC FT test protocol. [ABSTRACT FROM PUBLISHER]