This study examined the reliability and validity of the 20-meter shuttle test as a predictor of peak VO2 in Edinburgh school children. Thirty-three children (15 boys, 18 girls) performed three shuttle tests and three laboratory treadmill tests of peak VO2. Multiple regression analysis revealed that the prediction of peak VO2 (ml·kg−1·min−1) from shuttle run performance was improved by including skinfold thickness measurements in the prediction models, particularly with the female group. Predictive power was greatest for females when using maximal shuttle speed (kmhr−1) best of three repeat tests and triceps skinfold thickness (mm) (R 2 = .85, SEE = 2.4), and for males when using maximal shuttle speed (km·hr−1) best of three repeat tests and the sum of the triceps and subscapular skinfolds (R2 = .68, SEE = 3.23). When using shuttle run performance to predict peak VO2 (ml·kg−1·min−1) in children of this age group, body composition measures must be included in the equation.
Susan K. McVeigh, Andrew C. Payne and Shona Scott
Matt S. Stock, Travis W. Beck, Jason M. DeFreitas and Xin Ye
This study examined the peak torque and mechanomyographic (MMG) amplitude and mean frequency (MNF) responses during fatiguing isokinetic muscle actions. On four separate occasions, twenty men (mean ± SD age = 23 ± 3 years) performed 25, 50, 75, and 100 repeated maximal concentric isokinetic muscle actions of the dominant forearm flexors. During each muscle action, the MMG signal was detected from the biceps brachii with an accelerometer. The data were examined with linear regression and one-way repeated measures analyses of variance. The results indicated that the mean percent decline in peak torque value for the 25 repetition trial (25.6%) was significantly less than that for the 50 repetition trial (45.2%). Furthermore, the mean linear slope coefficient for the peak torque versus repetition number relationship for the 50 repetition trial was significantly less than that for the 100 repetition trial. There were no mean differences among the trials for the linear slope coefficients and y-intercepts for the MMG amplitude and MNF versus repetition number relationships. When detected with an accelerometer, the linear slope coefficients and y-intercepts for the MMG amplitude and MNF versus repetition number relationships were not sensitive enough to track the decline in muscle function during fatigue.
Robert P. Lamberts, Theresa N.C. Mann, Gerard J. Rietjens and Hendrik H. Tijdink
Iliac blood-flow restrictions causing painful and “powerless” legs are often attributed to overtraining and may develop for some time before being correctly diagnosed. In the current study, differences between actual performance parameters and performance parameters predicted from the Lamberts and Lambert Submaximal Cycle Test (LSCT) were studied in a world-class cyclist with bilateral kinking of the external iliac artery before and after surgery. Two performance-testing sessions, including a peak-poweroutput (PPO) test and a 40-km time trial (TT) were conducted before surgery, while 1 testing session was conducted after the surgery. Actual vs LSCT-predicted performance parameters in the world-class cyclists were compared with 82 symptom-free trained to elite male cyclists. No differences were found between actual and LSCT-predicted PPO before and after surgical intervention. However, there were differences between actual and LSCT-predicted 40-km TT time in the tests performed before the surgery (2:51and 2:55 min:s, respectively). These differences were no longer apparent in the postsurgery 40-km TT (2 s). This finding suggests that iliac blood-flow restrictions seem to mainly impair endurance performance rather than peak cycling performance. A standard PPO test without brachial ankle blood-pressure measurements might not be able to reflect iliac bloodflow restrictions. Differences between actual and LSCT-predicted 40-km TT time may assist in earlier referral to a cardiovascular specialist and result in earlier detection of iliac blood-flow restrictions.
Jonathon S. Schofield, Eric Parent, Justin Lewicke, Jason P. Carey, Marwan El-Rich and Samer Adeeb
Sit-to-stand transfer is a common prerequisite for many daily tasks. Literature often assumes symmetric behavior across the left and right side. Although this assumption of bilateral symmetry is prominent, few studies have validated this supposition. This pilot study uniquely quantifies peak joint moments and ground reaction forces (GRFs), using a Euclidian norm approach, to evaluate bilateral symmetry and its relation to lower limb motor-dominance during sit to stand in ten healthy males. Peak joint moments and GRFs were determined using a motion capture system and inverse dynamics. This analysis included joint moment contributions from all three body planes (sagittal, coronal, and axial) as well as vertical and shearing GRFs. A paired, one-tailed t test was used, suggesting asymmetrical joint moment development in all three lower extremity joints as well as GRFs (P < .05). Furthermore, using an unpaired two-tailed t test, asymmetry developed during these movements does not appear to be predictable by participants’ lower limb motor-dominance (P < .025). Consequently, when evaluating sit-to-stand it is suggested the effects of asymmetry be considered in the interpretation of data. The absence of a relationship between dominance and asymmetry prevents the suggestion that one side can be tested to infer behavior of the contralateral.
David Rodríguez-Rosell, Felipe Franco-Márquez, Fernando Pareja-Blanco, Ricardo Mora-Custodio, Juan M. Yáñez-García, José M. González-Suárez and Juan J. González-Badillo
To analyze the effects of low-load, high-velocity resistance training (RT) combined with plyometrics on physical performance in pre-peak-height-velocity (PHV) soccer players.
Thirty young soccer players from the same academy were randomly assigned to either a strength training (STG, n = 15) or a control group (CG, n = 15). Strength training consisted of full squat exercise with low load (45–58% 1RM) and low volume (4–8 repetitions/set) combined with jumps and sprints twice a week over 6 wk of preseason. The effect of the training protocol was assessed using sprint performance over 10 and 20 m, countermovement jump, estimated 1-repetition maximum, and average velocity attained against all loads common to pre- and posttests in full squat.
STG showed significant improvements (P = .004–.001) and moderate to very large standardized effects (ES = 0.71–2.10) in all variables measured, whereas no significant gains were found in CG (ES = –0.29 to 0.06). Moreover, significant test × group interactions (P < .003–.001) and greater between-groups ESs (0.90–1.97) were found for all variables in favor of STG compared with CG.
Only 6 wk of preseason low-volume and low-load RT combined with plyometrics can lead to relevant improvements in strength, jump, and sprint performance. Thus, the combination of field soccer training and lightweight strength training could be used for a greater development of the tasks critical to soccer performance in pre-PHV soccer players.
Khalid S. Almuzaini
The first purpose of the present study was to test sensitivity of the Wingate anaerobic test (WAnT) to alterations in resistance settings. The second purpose was to investigate whether using optimal braking force on WAnT enhances its relation with a 50-m dash, a vertical jump (VJ), or a standing long jump (LJ) tests. Twenty-three 12 year-old boys performed a 50-m dash, VJ, LJ, and WAnT using four braking force resistances (BFR; .065, .070, .075, and .080 kp/kg BM). Results revealed significant (p ≤ .05) differences among the four BFRs in peak power (PP) and in mean power (MP). Post hoc tests indicated significant differences among all of the four BFRs in PP and between the 0.065 and both the 0.075 and the 0.08 kp/kg BM in MP. Results of Pearson correlation coefficients indicated that using the optimal BFR for both PP and MP enhanced their relation with performance during the 50-m dash, VJ, and LJ tests. Also, partial correlation coefficients, controlling for body weight, height, percent fat, or body mass index supported these findings. It was concluded that for untrained, healthy 12-year-old boys, WAnT is sensitive to incremental alterations in resistance settings ranging from 0.065 to 0.080 kp/kg body mass. To be more specific, PP is sensitive to small increments in BFR, while MP is only sensitive to larger increments in BFR. Furthermore, optimizing resistance settings on WAnT enhances its relationship with anaerobic performance tasks, such as the 50-m dash, the VJ, and the LJ.