Grasping the handrails during treadmill walking does not alter sagittal plane kinematics of walking

OBJECTIVE

To determine whether grasping the handrails during treadmill walking affects sagittal plane kinematic parameters selected to describe walking style.

DESIGN

Crossover trial.

SETTING

A university motion analysis laboratory.

PARTICIPANTS

A convenience sample comprised of 15 apparently healthy college-age volunteers.

INTERVENTION

After being acclimatized to treadmill walking, subjects were videotaped while completing two treadmill walking bouts. Each bout was 10 minutes in duration and was conducted at a walking speed of 1.5m/sec. Subjects were instructed to grasp the handrails in one bout (GRASP) but to refrain from using the handrails in the other (FREE). Both bouts were conducted in a single session and were separated by a 10-minute rest period. The order in which subjects completed the bouts was randomized.

MAIN OUTCOME MEASURES

Five successive strides occurring during the last 30 seconds of each bout were digitized. The coordinate data were numerically filtered and the following parameters derived: stride length, percentage of stride cycle spent in double-support, and the hip, knee, and ankle angles at heel-strike and toe-off. The results for the five strides in each bout were averaged and the average value was used in the statistical analysis. The FREE and GRASP conditions were compared with t tests for dependent samples (p < or = .05).

RESULTS

There were no differences between the FREE and GRASP conditions for any of the parameters assessed.

CONCLUSIONS

Subjects may grasp the treadmill handrails without affecting sagittal plane kinematic parameters of walking style.

Is running style and economy affected by wearing respiratory apparatus?

The purposes of this investigation were to compare selected gait parameters characteristic of running without respiratory apparatus on a treadmill (NOR) with those displayed while wearing a mouthpiece-breathing valve apparatus (MP) and while wearing a respiratory face mask (MASK), and to compare the running economy (RE) measured during MP with that measured during MASK. Seventeen male volunteers [age = 32 +/- 5 yr (mean +/- SD); mass = 72.4 +/- 9.0 kg] performed three treadmill runs in randomly assigned order. All runs were identical in terms of duration (10 min), speed [200 m. min-2 (7.5 mph)], and grade (0%). During the last minute of each run, RE was measured and coordinate data were collected for determination of mechanical variables. The mechanical analyses were limited to 12 subjects. Stride length, vertical oscillation of the center of mass, hip and ankle range of motion, and average internal mechanical power output were not different for NOR, MP, and MASK. Knee range of motion was significantly less (P < or = 0.05) during MP than during NOR and MASK, primarily due to a significant reduction in maximum knee flexion during nonsupport. MASK RE was not significantly different (P > 0.05) from MP RE. It was concluded that wearing MP or MASK generally does not affect running style of individuals running at comfortable, submaximal running speeds and that RE measured with MP is not different from that measured with MASK.

Electromyographic analysis of bow string release in highly skilled archers

A predominant archery coaching tenet holds that the most effective means of releasing the bow string is by relaxation of the finger flexor muscles without activation of finger extensors. To evaluate the validity of this view, EMG patterns of the flexor digitorum superficialis and extensor digitorum muscles of the draw arm were examined using surface EMG electrodes in 15 highly skilled archers as each performed six shots. Each archer displayed consistent EMG patterns from shot-to-shot and two distinct flexor-extensor patterns were exhibited by the sample. The first, characterized by eight of the archers, supported the relaxation principle. For these archers, both flexor and extensor digitorum activity decreased markedly immediately prior to or at arrow release. The second pattern, characteristic of the remaining seven archers, contradicted the coaching tenet. While the flexor digitorum pattern was essentially the same as that described for the first pattern, the extensor digitorum displayed a marked increase in activity just prior to release, indicating that string release was facilitated by an active extension of the fingers. It was concluded that highly skilled archers do not predominantly reflect a release consistent with the coaching canon and that factors other than the string release mechanism discriminate the performances of skilled archers.