Shaher A. I. Shalfawi

The effect of high- vs. low-intensity training on aerobic capacity in well-trained male middle-distance runners.

Enoksen, E, Shalfawi, SAI, and Tønnessen, E. The effect of high- vs. low-intensity training on aerobic capacity in well-trained male middle-distance runners. J Strength Cond Res 25(3): 812-818, 2011-The purpose of this study was to examine the effect of 2 different intervention training regimes on &OV0312;o2max, &OV0312;o2max velocity (v&OV0312;o2max), running economy (RE), lactic threshold velocity (vLT), and running performance on a group of well-trained male middle-distance runners in the precompetition period. Twenty-six well-trained male middle-distance runners took part in the study. All participants were tested on &OV0312;o2max, v&OV0312;o2max, RE, lactate threshold (LT), vLT, and a performance test. The participants were matched according to their pretest results, then randomly assigned into 1 of 2 groups, a high-volume (70 km) low-intensity training group (HVLI-group); or a high-intensity low-volume (50 km) training group (HILV-group). No significant differences were found between the 2 groups on all measures both before and after the intervention period. Furthermore, the HILV-group had a marked increase in v&OV0312;o2max and vLT after the training period when compared with pretest. Both groups had a marked improvement in RE. The performance test showed that the HILV-group made 301 ± 886 m (1.0 ± 2.8 minutes) and the HVLI-group 218 ± 546 m (0.9 ± 1.8 minutes) in progress. The production of lactic acid was notably higher in the HILV-group (0.9 mmol) when compared with the pretest. The findings show that male middle-distance runners tested in this study improved in v&OV0312;o2max and vLT more when they train around LT, than training with low intensity for a short period of 10 weeks.

Performance effects of 6 weeks of aerobic production training in junior elite soccer players.

Abstract Ingebrigtsen, J, Shalfawi, SAI, Tønnessen, E, Krustrup, P, and Holtermann, A. Performance effects of 6 weeks of aerobic production training in junior elite soccer players. J Strength Cond Res 27(7): 1861–1867, 2013—This study investigates the performance effects of a 6-week biweekly anaerobic speed endurance production training among junior elite soccer players. Sixteen junior (age 16.9 ± 0.6 years) elite soccer players were tested in the Yo-Yo Intermittent Recovery test level 2 (IR2), 10-m and 35-m sprints, 7 × 35-m repeated-sprint ability (RSA) tests, countermovement jump and squat jump tests, and randomly assigned to either a control group (CG) performing their normal training schedule, which included 4 weekly soccer training sessions of approximately 90 minutes, or a training group performing anaerobic speed endurance production training twice weekly for 6 weeks in addition to their normal weekly schedule. We found that the intervention group significantly improved (p < 0.05) their performance in the Yo-Yo IR2 (63 ± 74 m) and 10-m sprint time (−0.06 ± 0.06 seconds). No significant performance changes were found in the CG. Between-group pretest to posttest differences were found for 10-m sprint times (p < 0.05). No significant changes were observed in the 35-m sprint times, RSA, or jump performances. These results indicate that short-term anaerobic production training is effective in improving acceleration and intermittent exercise performance among well-trained junior elite players.

The effect of different starting procedures on sprinters’ reaction time

Abstract We examined the effect of different false start rules and starters’ holding time on athletics sprinters’ reaction times. Reaction times from 210 female (25.2 ± 3.8 years) and 361 male (24.8 ± 3.8 years) 100 m sprinters, participating in international championships for seniors from 1997 to 2011, were analysed. Holding time calculations were based on television recordings from the analysed heats (n = 267). Mean reaction times have increased by 20% (0.03 s, P < 0.001) during a 15 year period due to stricter false start rules. Starters’ holding times were between 1.3 and 2.2 s for the analysed competitions. There was a small but significant relationship between reaction time and starters’ holding time for men (r = 0.16, P < 0.001) and women (r = 0.17, P < 0.001) between 1997 and 2003 and for men (r = 0.16, P < 0.001) in the time period 2003–2009, but not for women in the time period 2003–2009. While the interquartile range of reaction time decreased with longer holding time for female sprinters, the opposite trend was observed among the males. The present study demonstrates that world class sprinters’ reaction times and thereby their 100 m performance can vary 0.03–0.05 s depending on false start regulations and holding time.