Malissa Martin and Mary Kishman
Jose Antonio, John Uelmen, Ramsey Rodriguez and Conrad Earnest
The purpose of this study was to determine the effects of the herbal preparation Tribulus terrestris (tribulus) on body composition and exercise performance in resistance-trained males. Fifteen subjects were randomly assigned to a placebo or tribulus (3.21 mg per kg body weight daily) group. Body weight, body composition, maximal strength, dietary intake, and mood states were determined before and after an 8-week exercise (periodized resistance training) and supplementation period. There were no changes in body weight, percentage fat, total body water, dietary intake, or mood states in either group. Muscle endurance (determined by the maximal number of repetitions at 100—200% of body weight) increased for the bench and leg press exercises in the placebo group (p < .05; bench press ±28.4%. leg press ±28.6%), while the tribulus group experienced an increase in leg press strength only (bench press ±3.1 %, not significant; leg press ±28.6%, p < .05). Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.
C. Collin Herb, Lisa Chinn and Jay Hertel
Lateral ankle sprain (LAS) is one of the most common injuries in active individuals. Chronic ankle instability (CAI) is a condition that commonly occurs after LAS and is associated with long-term disability and a high risk of multiple ankle sprains. Ankle taping is a commonly used intervention for the prevention of ankle sprains.
To analyze the ankle-joint coupling using vector coding during walking and jogging gait with the application of ankle tape and without ankle tape in young adults with and without CAI.
Observational laboratory study design. Patients walked and jogged on an instrumented treadmill while taped and not taped. Fifteen strides for each subject were collected and analyzed using a vector-coding technique to compare magnitude coupled motion, ratio of coupled motion, and the variability (VCV) within groups. Within-group means and 90% confidence intervals (CI) were compared between the taped and nontaped condition, and where the CIs did not overlap was considered significant.
A 12-camera 3D motion-capture system with instrumented treadmill.
12 patients with CAI and 11 healthy controls.
Main Outcome Measures:
Magnitude to coupled motion, ratio of coupled motion, and the VCV of shank–rear-foot joint coupling.
Magnitude of coupled motion and VCV were significantly lower in the taped condition than in the nontaped condition in both groups. Magnitude differences were identified near initial contact during walking and during swing phase of jogging. VCV differences were identified throughout the gait cycle at both walking and jogging. No differences were identified in theta between tape and nontaped conditions.
A decrease in the magnitude of coupled motion and VCV may represent a protective mechanism of ankle taping in CAI and healthy patients during gait.
Andrea Weber and Herb Amato
Jeff G. Konin, Herb K. Amato and Holly Brader
James R. Funk, Richard A. Watson, Joseph M. Cormier, Herb Guzman and Enrique Bonugli
Previous studies on neck muscle strength and motion have assumed or imposed varying constraints on the heads and bodies of the subjects. In this study, we asked 20 subjects to vigorously shake their heads 5−10 times in a completely unconstrained manner. The kinematics and kinetics of the head and neck were measured from video analysis and instrumentation mounted inside the mouth. Subjects shook their heads at self-selected tempos ranging from 1.9−4.7 Hz over a 20−91° range of motion. The motion of each subject’s head could be approximated by a fixed center of rotation that was typically located in the midcervical spine, but varied widely among subjects. Significant differences between men and women were observed. Peak head accelerations were low (4.3 ± 1.1 g and 250 ± 103 rad/s2 for men, 3.0 ± 0.9 g and 182 ± 58 rad/s2 for women) and estimated peak generated neck moments at C7/T1 were comparable to values reported in isometric neck strength studies (47 ± 14 N·m in extension and 22 ± 9 N·m in flexion for men, 25 ± 8 N·m in extension and 9 ± 7 N·m in flexion for women).
Jennifer Ostrowski, C. Collin Herb, James Scifers, Teraka Gonzalez, Amada Jennings and Danvirg Breton
Background: ThermoStim Probe (TSP) has recently joined the market as a superficial heating modality. Although there is limited research into the intramuscular heating capability of superficial heating modalities in general (moist hot pack [MHP], paraffin, warm whirlpool), no previous research has examined intramuscular heating capability of TSP. Objective: Evaluate rate and magnitude of intramuscular heating via TSP compared with hydrocollator MHP, and determine if TSP can increase tissue temperature 3°C–4°C (vigorous heating range). Design: Repeated-measures counterbalanced study. Setting: Multisite trial; 2 college/university research laboratories. Patients or Other Participants: A total of 18 healthy college-aged participants (11 females and 7 males, age: 23.0 [2.1] y, weight: 74.64 [18.64] kg, height: 168.42 [9.66] cm, subcutaneous adipose: 0.71 [0.17] cm) with calf subcutaneous adipose <1.2 cm. Interventions: MHP and TSP were applied to the posterior aspect of the nondominant calf for 20 minutes; participants underwent each treatment in a counterbalanced order. Main Outcome Measurements: Muscle temperature at a depth of 1.5 cm was measured via 21-gauge catheter thermocouple. Temperatures were recorded at baseline and during the 20-minute treatment. Results: There was a significant treatment-by-time interaction during the treatment period (F 5,85 = 14.149, P < .001), as well as significant main effects for treatment (F 1,17 = 7.264, P = .02) and for time (F 5,85 = 34.028, P < .001). Muscle temperature increased an average of 1.7° (0.9°) for the MHP and 0.6° (1.0°) for the TSP. Pairwise comparisons of the interaction (using least significant difference adjustment for multiple comparisons) indicated that MHP heated faster than TSP at minutes 12 (P = .02), 16 (P = .002), and 20 (P = .001). There was no significant correlation between subcutaneous adipose thickness and maximum temperature increase obtained with either MHP (r = −.033, P = .90) or TSP (r = −.080, P = .75). Conclusions: MHP increased intramuscular temperature significantly more than TSP; however, neither modality was capable of producing a 3°C–4°C temperature increase associated with increased tissue extensibility.
C. Collin Herb, Lisa Chinn, Jay Dicharry, Patrick O. McKeon, Joseph M. Hart and Jay Hertel
Chronic ankle instability (CAI) results in longstanding symptoms and subjective feelings of “giving way” following initial ankle sprain. Our purpose was to identify differences in joint coupling and variability between shank internal/external rotation and rearfoot inversion/eversion throughout the gait cycle of CAI subjects and healthy controls. Twenty-eight young adults participated (CAI, n = 15, control, n = 13). Kinematics were collected while walking and jogging on a treadmill. A vector coding method in which direction (θ) and magnitude of the angle-angle relationship and stride-to-stride variability (VCV) in shank-rearfoot coupling were calculated. In walking, the CAI group demonstrated lower θ, indicating a greater proportion of rearfoot-to-shank motion, compared with the control group in early and late swing. The CAI group had higher magnitude, indicating greater combined motion between the two segments, in early swing, but lower magnitude, indicating less combined motion, during late swing. The CAI group also had lower VCV measures, indicating less stride-to-stride variability during stance. In jogging, the CAI group had lower θ measures than the control group during stance and swing. Differences in shank-rearfoot coupling of the CAI group may be related to changes in sensorimotor control and lead to further instances of instability.
Mark A. Feger, Luke Donovan, C. Collin Herb, Geoffrey G. Handsfield, Silvia S. Blemker, Joseph M. Hart, Susan A. Saliba, Mark F. Abel, Joseph S. Park and Jay Hertel
Context: Patients with chronic ankle instability (CAI) have demonstrated atrophy of foot and ankle musculature and deficits in ankle strength. The effect of rehabilitation on muscle morphology and ankle strength has not previously been investigated in patients with CAI. Objective: Our objective was to analyze the effect of impairment-based rehabilitation on intrinsic and extrinsic foot and ankle muscle volumes and strength in patients with CAI. Design: Controlled laboratory study. Setting: Laboratory. Patients: Five young adults with CAI. Intervention: Twelve sessions of supervised impairment-based rehabilitation that included range of motion, strength, balance, and functional exercises. Main Outcome Measures: Measures of extrinsic and intrinsic foot muscle volume and ankle strength measured before and after 4 weeks of supervised rehabilitation. Novel fast-acquisition magnetic resonance imaging was used to scan from above the femoral condyles through the entire foot. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a hand-held dynamometer. Results: Rehabilitation resulted in hypertrophy of all extrinsic foot muscles except for the flexor hallucis longus and peroneals. Large improvements were seen in inversion, eversion, and plantar flexion strength following rehabilitation. Effect sizes for significant differences following rehabilitation were all large and ranged from 1.54 to 3.35. No significant differences were identified for intrinsic foot muscle volumes. Conclusion: Preliminary results suggest that impairment-based rehabilitation for CAI can induce hypertrophy of extrinsic foot and ankle musculature with corresponding increases in ankle strength.
Thomas B. Walker and Robert A. Robergs
Rhodiola rosea is an herb purported to possess adaptogenic and ergogenic properties and has recently been the subject of increased interest. The purpose of this article was to review and summarize recent investigations of the potential performance-enhancing properties of Rhodiola rosea. Such studies have generated equivocal results. Several investigations conducted in Eastern Europe have indicated that Rhodiola rosea ingestion may produce such positive effects as improved cognitive function and reduced mental fatigue. Other research from this region has illustrated enhanced endurance exercise performance in both humans and rats. Studies conducted in Western Europe and in North America have indicated that Rhodiola rosea may possess substantial antioxidant properties but have produced mixed results when attempting to demonstrate an ergogenic effect during exercise in humans.