The purpose of this study was to compare the effects of four different treatments on the control of the amount and rate of foot pronation while running. The four treatments were the reverse 8-stirrup taping technique, the low-dye taping technique, prescribed rigid orthotic devices, and no support in the running shoe. Six intercollegiate cross-country runners were filmed from the rear while running on a treadmill, and the film data were analyzed. A two-way MANOVA indicated no significant overall treatment effect for the dependent variables. A one-way ANOVA indicated that the reverse 8-stirrup taping technique significantly reduced the amount of maximum pronation when compared to shoes-no support and low-dye taping techniques. The reverse 8-stirrup also had significantly fewer degrees of total rear foot movement when compared to the low-dye taping technique. No other significant comparisons were realized. It was concluded that the reverse 8-stirrup would be as effective a treatment for excessive pronation in runners as the prescribed rigid orthotic device.
Contractile and histochemical properties of the human gastrocnemius muscle were compared in 21 male athletes ranging from 20 to 29 years of age. Surface electrical stimulation was used to determine muscle twitch parameters. The contractile variables of the muscle twitch were: latency (L), time to peak force (TPF, and TPFA, peak force (Pf, and Pfd, half-contraction The use of electrically evoked twitch or maximal tetanic contractions under static conditions has been well established in the study of human contractile function. In most human studies, motor units have been characterized in terms of their peak twitch force (Po, time to peak force (TPF), and half-relaxation time ('/z RT) (2, 22,23,25,30,34,35). Although there has been a number of studies in humans where the mechanical properties of the twitch and tetanus have been measured, no studies investigating the relationship between whole muscle twitch and the histochemical profile of human muscle were identified.Based on animal studies, similar in vivo electrical stimulation techniques have been employed with humans to measure the contractile properties of a muscle in relation to its histochemical fiber type parameters (24,28,33,36). The in vitro preparations of Moulds et al (21) demonstrated that the speed at relaxation, expressed as a reciprocal, after a brief tetanus correlated significantly (r = 0.91) with the percentage of fast twitch (FT) fibers. Faulkner et al(9) also reported a strong correlation (r = 0.94) between contractile speed measurements and fiber type distribution using isolated preparations of human and animal tissue. Rice et al(23) demonstrated for the first time with intact human triceps surae muscle significant positive relationships between percentage of slow twitch fibers (% ST) and time to peak force (TPF) (r = 0.49) and between O/ O ST and the ratio of tetanic forces in Newtons at 10 to 50 hertz (r = 0.55). The purpose of this study was to compare the contractile properties from an electrically stimulated twitch with histochemically determined fiber type parameters of the gastrocnemius muscle. METHODS Subjects' School of Health, Physical Education and Reaeatii, Bowling Green State lhiversity 0190-601
The purpose of the study was to compare the contractile properties determined from an electrically stimulated twitch with histochemically determined fibre type parameters of the human triceps surae. Muscle samples were obtained from the medial head of the gastrocnemius of ten male athletes. Ages ranged from 20 to 29 years. Muscle samples from the belly of the medial gastrocnemius muscle were obtained using the needle biopsy technique. The samples were treated histochemically for myosin ATPase to classify the fibres as either slow twitch (ST) or fast twitch (FT) and to determine fibre areas. Surface electrical stimulation was used to determine muscle twitch parameters. The contractile variables of the muscle twitch were latency (L), time to peak force (TPF), peak force (PF), half-contraction time (1/2 CT) and half-relaxation time (1/2 RT). Backward elimination procedures for dependent variables were used to determine which contractile properties best represented the histochemical profile of the muscles. Prediction formulas were developed for FT and ST percentages (R2 = 0.98, p < 0.001), relative area percentage (R2 = 0.87, p < 0.001), and ST area (R2 = 0.85, p < 0.01). It was concluded that the use of the electrotensiometer (ETM) protocol was a valid testing procedure when studying physiological relationships of histochemical properties in intact human skeletal muscle.
The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.
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