Research in Sport Medicine and Technology

Introdiction and Aim: Nowadays, due to the epidemic of sports supplements, the effects of these
supplements on athletic performance require analysis and evaluation.The aim of the present study was to
investigate the effect of arginine supplementation for one week on oxygen uptake kinetics and time to
exhaustion in female taekwondo athletes.
Method: In this semi-experimental study with pretest – posttest design, eighty female taekwondo athletes
(age: 19.88±2.33 y, height: 167.53±6.04 cm, weight: 60.98±2.4 kg) were randomly assigned to argenine
supplementation (n=9) or placebo (n=9) groups. Subjects performed the incremental test (initially, the work
load 50 watts and 30 watts increase in workload every minutes, as long as subjects will be able to maintain
the highest pedal rate and the failure to reach). To simulate a taekwondo match day test session consisted
of three maximal incremental test intervals (1 to 2 hours). The experimental group was supplemented with
6g arginine powder and placebo group received 6g microcrystalline cellulose each day for one week.
Seven days after, post test accordingly pretest was used by all subjects. Pulmonary gas exchange was
measured by gas analyzer to breath-by breath method. Oxygen uptake kinetics variables (oxygen deficit,
time constant 1, time constant 2) were evaluated by gas analyzer with breath-by breath method. Data was
analyzed using two ways ANOVA.
Results: The time to exhaustion was extended following consumption of arginine (p<0.05). Also the
findings showed that arginine supplementation resulted in a speeding of the oxygen uptake kinetic (oxygen
deficit, time constant 1, time constant 2) (p<0.05).
Conclusion: It seems that arginine supplementation improves oxygen kinetics factors and time to
exhaustion in female taekwondo athletes.

Hamstrings (Hams) to Quadriceps (Quadr) strength ratio is known as a risk factor for Anterior Cruciate Ligament (ACL) injury and affects by knee and hip flexion angles. Gluteus Maximus (Gmax) muscle acts as a synergist for Hams in hip extension in a closed kinetic chain. The aim of this study was to investigate the effect of Gmax strengthening exercises on the kinetic and kinematic risk factors of ACL injury when single-leg landing from a jump. 25 volunteer women aged 18-30 years were assigned into control (n =13) and experimental (n =12) groups. Maximum isometric strength of Gmax, hip and knee joint angles and ground reaction force (GRF) was measured at landing, by dynamometer, 2D imaging and foot scan respectively,. After 8 weeks of 3 sessions of Gmax resistance training, Following the significant within-subject difference for GRF (F=5.245, P=0.032) by using Two-way mixed model ANOVA, Pre and post-test Differences were significant with 16.63% decrease (P= 0.038, t=2.354). Differences between pre and post-test peak force, time to peak, mean joint angles, impact and load rate were not significant (α = 0.05). According to a 4.55% and 3.47% increase in Gmax strength and time to peak force, and considering the fact that at the beginning of landing, the mechanical advantage of Hams is lower than that of Gmax, the risk of ACL injury could be reduced by reducing GRF following an increase in the Gmax strength.