Time series analysis: evaluating performance trends within resistance exercise sessions.

Recent technical advances allow coaches, sport scientists, and researchers to take frequent performance measurements, both within a training session and across a period of training. These performance measurements should demonstrate a systematic pattern, based on physiologic responses and adaptations; however, variability in performance, resulting from both physiologic and psychological factors, may hamper interpretation of these measures. This report describes the moving-average method used in time series analysis to reduce variability and elucidate systematic patterns during high-power resistance exercise. Men (n = 10) power athletes performed 3 high-power resistance exercise sessions (75% 1 repetition maximum [RM]/5 repetitions x 12 sets; 85% 1RM/3 x 15; 95% 1RM/1 x 20). Average barbell power was recorded during the exercise sessions using three-dimensional motion analysis. High-power resistance exercise resulted in increases in performance early in the exercise sessions (p < 0.05) and decreases in performance after the mid-point in the exercise session (p < 0.05). Deviations in performance responses were observed, which obscured the systematic pattern. A 3-point moving average reduced the effects of the deviations, allowing a systematic pattern, consistent with known acute physiologic responses, to be identified. Acutely, exercise elicits changes in performance that should follow a systematic pattern. Determining the systematic pattern associated with various exercise and loading parameters can be utilized to optimize such parameters to maximize the training stimulus while minimizing fatigue. The use of time series analysis, specifically the moving average technique, reduces within-session variability allowing the systematic pattern to be determined.

Effects of unstable surface training on measures of balance in older adults.

The purpose of this investigation was to examine the effects of a 5-week, low-cost unstable surface balance training program in sexagenarians. Nineteen men and women (60-68 years; 83.7 +/- SD kg) were randomly assigned to a control or training group. The training group performed various balance activities on air-filled rubber disks for 5 weeks. Each thrice-weekly session was supervised, and progression was based on proficiency. While in an upright position, static balance (length of path [LOP] of the center of pressure) was assessed in both eyes-open and eyes-closed states for each leg separately as well as for both legs. Participants also performed the timed up-and-go (TUG) test and completed the Activity-specific Balance Confidence (ABC) questionnaire. A significant group x time effect for the ABC questionnaire was found (p = 0.04). Tukey post hoc analysis indicates that the balance training program increased self-perceived balance confidence (p < 0.01). No significant group x time interactions were noted for TUG or LOP. Because no objective measure of balance or function was changed, the increase in ABC may be spurious. Unstable surface training may not be effective in improving balance among persons for whom balance is not problematic. However, the large number of acute training variables in such a program leaves opportunity for further research in this paradigm.