Gait data are commonly presented as an average of many trials or as an average across participants. Discrete data points (eg, maxima or minima) are identified and used as dependent variables in subsequent statistical analyses. However, the approach used for obtaining average data from multiple trials is inconsistent and unclear in the biomechanics literature. This study compared the statistical outcomes of averaging peaks from multiple trials versus identifying a single peak from an average profile. A series of paired-samples t tests were used to determine whether there were differences in average dependent variables from these 2 methods. Identifying a peak value from the average profile resulted in significantly smaller magnitudes of dependent variables than when peaks from multiple trials were averaged. Disagreement between the 2 methods was due to temporal differences in trial peak locations. Sine curves generated in MATLAB confirmed this misrepresentation of trial peaks in the average profile when a phase shift was introduced. Based on these results, averaging individual trial peaks represents the actual data better than choosing a peak from an average trial profile.
Kevin D. Dames, Jeremy D. Smith and Gary D. Heise
Roy J. Shephard and François Trudeau
This article looks retrospectively at lessons learned from the Trois-Rivières physical education study. A brief review of the experimental design shows 546 students assigned by class cohort to either an additional 5 hours of quality physical education per week in grades 1 through 6, or a control treatment (minimal physical education by the homeroom teacher). Strengths of the study include a quasi-experimental design, a prolonged and well-defined intervention, assessment of compensation for the program, continuation of observations into middle age, collection of data in urban and rural environments, consistency of teaching staff and technical personnel, documentation of changes in academic achievement, assessment of bone maturation, a carefully constructed database, and control for cross-contamination. Limitations include some secular change, limited information on pubertal stages, difficulty in generalizing findings to an English-speaking environment, and some rigidity in the statistical design. The study demonstrates that cardiorespiratory function, muscle strength, and field performance can all be enhanced in primary school with no negative impact on academic work. Further, attitudes, behavior, and function are favorably influenced in adults. Future studies should seek out stable populations, define interventions closely, contract with participants for a long-term follow-up, and assess the immediate and long-term impact on health and function. Above all, there is a need for a dedicated principal investigator who will devote his or her entire career to the longitudinal study.
Steven R. McAnulty, David C. Nieman, Lisa S. McAnulty, Worley S. Lynch, Fuxia Jin and Dru A. Henson
Consumption of plant flavonoids, antioxidants, and n-3 fatty acids is proposed to have many potential health benefits derived primarily through antioxidant and anti-inflammatory activities. This study examined the effects of 1,000 mg quercetin + 1,000 mg vitamin C (QC); 1,000 mg quercetin, 1,000 mg vitamin C, 400 mg isoquercetin, 30 mg epigallocatechin gallate, and 400 mg n-3 fatty acids (QFO); or placebo (P), taken each day for 2 wk before and during 3 d of cycling at 57% Wmax for 3 hr, on plasma antioxidant capacity (ferricreducing ability of plasma [FRAP], oxygen-radical absorbance capacity [ORAC]), plasma oxidative stress (F2-isoprostanes), and plasma quercetin and vitamin C levels. Thirty-nine athletes were recruited and randomized to QC, QFO, or P. Blood was collected at baseline, after 2 wk supplementation, immediately postexercise, and 14 hr postexercise. Statistical design used a 3 (groups) × 4 (times) repeated-measures ANOVA with post hoc analyses. Plasma quercetin was significantly elevated in QC and QFO compared with P. Plasma F2-isoprostanes, FRAP, and vitamin C were significantly elevated and ORAC significantly decreased immediately postexercise, but no difference was noted in the overall pattern of change. Post hoc analyses revealed that the QC and QFO groups did not exhibit a significant increase in F2-isoprostanes from baseline to immediately postexercise compared with P. This study indicates that combining flavonoids and antioxidants with n-3 fatty acids is effective in reducing the immediate postexercise increase in F2-isoprostanes. Moreover, this effect occurs independently of changes in plasma antioxidant capacity.
Kristof Kipp, Michael T. Kiely, Matthew D. Giordanelli, Philip J. Malloy and Christopher F. Geiser
-subject statistical design of the current study, the lack of squat-jump data should not influence the inferences related to the decreases in concentric work during the DJ that were observed from the greater drop heights or any proposed changes in stretch-shortening-cycle function. Finally, the contact times for all
Leigh Ann Ganzar, Nalini Ranjit, Debra Saxton and Deanna M. Hoelscher
doi:10.4278/ajhp.130125-QUAN-47 24460004 10.4278/ajhp.130125-QUAN-47 19. Pérez A , Hoelscher D , Frankowski R , Day R , Lee E . Statistical design, sampling weights and weight adjustments of the School Physical Activity and Nutrition (SPAN) population-based surveillance 2009–2010 study
Harsh H. Buddhadev, Daniel L. Crisafulli, David N. Suprak and Jun G. San Juan
) was used for the between-group contrast. The statistical design used in this study is identical to the one used by Hunt et al, 11 contrasting interlimb asymmetry in ACL-deficient individuals and healthy controls. Independent t tests were used to determine if the groups differed in KOOS scores for
Andrew D. Nordin and Janet S. Dufek
– 638 . PubMed 9148096 19. James CR , Bates BT . Experimental and statistical design issues in human movement research . Meas Phys Educ Exerc Sci . 1997 ; 1 ( 1 ): 55 – 69 . 10.1207/s15327841mpee0101_4 10.1207/s15327841mpee0101_4 20. Newell KM . Constraints on the development of coordination
Travis J. Peterson and Jill L. McNitt-Gray
impulse generated by players was not significantly different between conditions across the group (Figure 3 ). Player-specific differences in net angular impulse were discovered via the within-player statistical design in some cases. Between modified leg conditions, target leg angular impulse increased
Louise M. Burke and Peter Peeling
who receive both supplement and placebo, with different order of treatment being balanced within group. Can be fully controlled (baseline and treatment measurement for both experimental and placebo) or simple crossover (no baseline measurement) when time or resources are limited. Strong statistical
Christopher Tack, Faye Shorthouse and Lindsy Kass
, K.R. ( 2011 ). Statistical design considerations in animal studies published recently in cancer research . Cancer Research, 71 ( 2 ), 625 . PubMed doi:10.1158/0008-5472.CAN-10-3296 10.1158/0008-5472.CAN-10-3296 Higgins , J.P. , Altman , D.G. , Gøtzsche , P.C. , Jüni , P. , Moher , D