Muscle activation was measured using EMG in 28 males (n = 28) while participants caught visually identical balls of known and unknown weights (50, 1.32, 2.18, and 2.99 kg) under variable (1–10s) and constant (3s) foreperiods. EMG integrals were computed for three time intervals before the catch (anticipatory), and one after (compensatory). Load uncertainty caused the CNS to use an anticipatory strategy characterized by preparation to catch balls of an unknown weight by utilizing about 92% of the muscle activation used to catch the heaviest possible ball under the known weight condition. The CNS appeared to scale anticipatory muscle activation to afford an opportunity to catch a ball of an unknown weight between .50 and 2.99 kg. The constant 3s foreperiod, which permitted temporal anticipation, did not influence the anticipatory neuromotor strategy adopted by the CNS to cope with load uncertainty. Load uncertainty also altered compensatory neuromotor control in catching.
William P. Berg and Michael R. Hughes
William P. Berg and Brian A. Lapp
The purpose of this study was to examine the effect of a practical resistance training program for the lower extremities on mobility in independent, community-dwelling older adults. Twenty-two volunteers with a mean age of 72.9 years underwent two identical pretests 1 month apart. Lower extremity strength, locomotor stability, preferred gait velocity, and step lime in obstacle clearance were assessed. Participants then engaged in an 8-week resistance training program for the lower extremities using adjustable ankle weights. Following a posttest, a repeated-measures ANOVA was used to determine whether changes in strength and mobility when the treatment was interjected differed from when it was not. Results indicated that the training had a limited effect on strength and no effect on mobility. The feasibility of practical resistance training interventions to counteract muscle weakness and associated immobility in independent older adults is discussed.
William P. Berg and Nancy L. Greer
This study determined the kinematics of the final 11 steps of the long jump approach (LJA) for 19 novice long jumpers. Associations between takeoff accuracy and jump performance were identified, and comparisons of LJA kinematics were made with previous investigations of horizontal jumps performed by expert long jumpers. Results indicated that absolute takeoff error was not an important determinant of jump distance for the novice long jumpers. Additionally, novice jumpers differed from expert jumpers in terms of the relationships among specific variables. The results suggest that kinematic variables that appear to be causally related to jump performance in experts may not piay a similar role in the performance of novices. Hypotheses for these differences were offered. Differences between the LJAs of novice and expert long jumpers warrant further investigation, so that their origins can be determined and used to develop effective training regimes.
Christina M. Ohlinger, Thelma S. Horn, William P. Berg and Ronald Howard Cox
The purpose of this study was to assess participants’ ability to perform tasks requiring attention, short term memory, and simple motor skill while sitting, standing or walking at an active workstation.
Fifty participants completed the Stroop Color Word test (SCWT), Auditory Consonant Trigram test (ACTT), and Digital Finger Tapping test (DFTT) while sitting, standing and walking 1.6 km/h at an active workstation.
A significant difference was found for DFTT, but no differences across conditions were found on ACTT or SCWT. Examination of the linear contrasts and post hoc means comparison tests revealed significant differences in DFTT scores between sitting and walking (t = 2.39 (49) P < .02) and standing and walking (t = 2.28 (49) P < .03). These results indicate that adding the walking task to the ACTT and SCWT conditions results in no decrement in performance on these tasks. Conversely, adding the walking task to the DFTT condition results in reduced performance on the DFTT task.
These results further support the potential of active workstations to increase physical activity in the workplace without compromising cognitive capabilities.