Bedrettin Akova

Acute effects of static and dynamic stretching on leg flexor and extensor isokinetic strength in elite women athletes

The aim of this study was to explore the effects of static and dynamic stretching of the leg flexors and extensors on concentric and eccentric peak torque (PT) and electromyography (EMG) amplitude of the leg extensors and flexors in women athletes. Ten elite women athletes completed the following intervention protocol in a randomized order on separate days: (a) non‐stretching (control), (b) static stretching, and (c) dynamic stretching. Stretched muscles were the quadriceps and hamstring muscles. Before and after the stretching or control intervention, concentric and eccentric isokinetic PT and EMG activity of the leg extensors and flexors were measured at 60 and 180°/s. Concentric and eccentric quadriceps and hamstring muscle strength at both test speeds displayed a significant decrease following static stretching (P<0.01–0.001). In contrast, a significant increase was observed after dynamic stretching for these strength parameters (P<0.05–0.001). Parallel to this, normalized EMG amplitude parameters exhibited significant decreases following static (P<0.05–0.001) and significant increases following dynamic stretching (P<0.05–0.001) during quadriceps and hamstring muscle actions at both concentric and eccentric testing modes. Our findings suggest that dynamic stretching, as opposed to static or no stretching, may be an effective technique for enhancing muscle performance during the pre‐competition warm‐up routine in elite women athletes.

Exercise-induced oxidative stress and muscle performance in healthy women: role of vitamin E supplementation and endogenous oestradiol.

Abstract The purpose of this study was to investigate the individual and combined antioxidant effects of menstrual cycle phase-related alterations in blood serum oestradiol concentrations and of dietary vitamin E supplementation on exercise-induced oxidative stress and muscle performance. A group of 18 sedentary women, aged 19–35 years, were given supplements of 300 mg α-tocopherol (n=10) or placebo (n=8) daily during the course of two menstrual cycles. The subjects exercised the knee isokinetically to exhaustion after cycling submaximally at 50% maximal oxygen uptake during the menstrual and preovulatory phases of their menstrual cycles. Blood samples were taken before and after the exercise, to evaluate haematocrit, plasma lactic acid and malondialdehyde concentrations, erythrocyte antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and apolipoprotein B containing lipoprotein (non-high density lipoprotein, HDL, fraction) oxidation. Serum vitamin E, follicle stimulating hormone, luteinizing hormone and oestradiol concentrations were measured in pre-exercise blood samples. Neither vitamin E supplementation nor oestradiol concentrations influenced SOD and GPx activities or the susceptibility of the non-HDL fraction to oxidation while at rest. Plasma malondialdehyde concentration was unaffected by exercise, however significant reductions in erythrocyte SOD and GPx activities and increased susceptibility of the non-HDL fraction to oxidation were noted after exercise. Exercise-induced changes were reduced when oestradiol concentration was high in the preovulatory phase, independent of the serum vitamin E concentrations. In addition, both pre- (r=0.58, P < 0.05) and post-exercise (r=0.73, P < 0.001) GPx activities in placebo administered subjects were positively correlated with oestradiol concentrations. In conclusion, these findings suggest a better protective role of oestradiol against oxidative injury, compared to vitamin E. Exhausting muscle performance was, however, not influenced by vitamin E supplementation and/or cycle-phase related changes in oestradiol concentrations.

Effects of age on the reciprocal peak torque ratios during knee muscle contractions in elite soccer players

To investigate the effects of age on the reciprocal peak torque ratios during knee muscle contractions, 25 elite male soccer players, aged 22.3±3.8 yr (18–28), volunteered for the present study. The players were grouped as adult (>21 years, n=13) and young players (≤21 years, n=12). Maximal concentric (CON) and eccentric (ECC) isokinetic thigh muscle strength was measured at angular velocities of 30°, 180°, 240° and 300°/s. ECC and CON peak torques of knee flexors (hamstring, HAM) and CON peak torques of knee extensors (quadriceps, QUA) in the dominant knee were greater (P<0.05) in adult players than in young players at 180, 240 and 300°/s. ECC HAM/CON QUA peak torque ratio at 300°/s was greater (P<0.05) for adult players compared to young players in the dominant knee but not in the nondominant knee. Furthermore, conventional HAM/QUA peak torque ratios of the dominant knee at all angular velocities for ECC contraction were higher (P<0.05) in adult players than in young players. In conclusion, the findings of the present study indicate that the reciprocal torque ratio is influenced by age in the dominant knee of elite soccer players. Because there was no effect of age for the nondominant leg, the findings of the present study are more likely to be the result of the training background of the players than their age.

Early Versus Late Start of Isokinetic Hamstring-Strengthening Exercise After Anterior Cruciate Ligament Reconstruction With Patellar Tendon Graft

Backgound Hamstring strengthening after anterior cruciate ligament reconstruction is a vital component of the rehabilitation program. Purpose The objective of this trial was to investigate the effects of hamstring isokinetic training used in the early phase of the rehabilitation program on the stability, strength, symptoms, and functional outcomes of patients throughout 12 months after anterior cruciate ligament surgery. Study Design Randomized controlled clinical trial; Level of evidence, 2. Methods Forty-eight men underwent anterior cruciate ligament reconstruction with an ipsilateral bone—patellar tendon—bone autograft. The patients were randomly assigned to perform daily isokinetic hamstring exercises at postoperative 3 weeks (group I) or to perform daily isokinetic hamstring exercises at postoperative 9 weeks (group II). The patients were evaluated monthly for the first 4 months and at the 12th month for postoperative hamstring and quadriceps strength, as well as for knee function via the Cincinnati Knee Rating Scale and International Knee Documentation Committee form. Results Hamstring isometric strength at 30° of knee flexion (at the first and second months) and concentric isokinetic strength (at 2, 3, 4, and 12 months) at the angular velocity of 60 deg/s were significantly (P < .05-.01) greater in group I compared with group II. Average scores of the Cincinnati Knee Rating Scale for symptoms were significantly (P < .05-.001) higher in group I compared with group II at all evaluation periods. Walking and stair-climbing scores at 1, 2, 3, and 4 months and squatting score at all evaluation periods were also better (P < .05-.01) in group I compared with group II. In addition, group I exhibited better (P < .01-.001) Lachman test results compared with group II for all postoperative evaluation periods. The International Knee Documentation Committee final rating scores were significantly (P < .01) greater at 2, 3, and 4 months in group I compared with group II. Conclusion The results of this study suggest that hamstring as well as quadriceps strength can be increased via early hamstring strengthening after anterior cruciate ligament reconstruction with no negative impact on knee function.

Continuous versus separate isokinetic test protocol: The effect of estradiol on the reproducibility of concentric and eccentric isokinetic measurements in knee muscles☆

OBJECTIVE To investigate the effects of estradiol on the reliability of concentric and eccentric isokinetic measurements of knee muscles and to compare the reproducibility of measurements in a continuous test protocol and a separate test protocol. DESIGN Repeated measurements. SETTING A university exercise physiology laboratory. PARTICIPANTS Twenty healthy sedentary women volunteers, aged 19 to 37 years, who had regular menstrual cycles (ranging from 27 to 35 days). Subjects were randomly divided into two groups: continuous test group (n = 10) and separate test group (n = 10) and tested at the menstrual phase (days 1 to 3) and preovulatory phase (days 12 to 14) in both legs. METHODS Continuous reciprocal flexion-extension contractions were used in the continuous test group, and separated flexion and extension contractions were used in the separate test group. Four different test protocols were designed to determine the effects of test mode and number of contractions on the isokinetic measurements: Group A, 4 reciprocal flexion-extension repetitions at each angular velocity of 60 degrees/sec and 180 degrees/sec in one leg in the continuous test group; Group B, 4 and 20 reciprocal flexion-extension repetitions at 60 degrees/sec and 180 degrees/sec, respectively, in the contralateral leg in the same group; Group C, 4 repetitions in extensors and flexors at each angular velocity of 60 degrees/sec and 180 degrees/sec with a 5-minute rest between the two muscle groups in one leg in the separate test group; and Group D, 4 repetitions at 60 degrees/sec and 20 repetitions at 180 degrees/sec for extensors and flexors with a 5-minute rest between the two muscle groups in the contralateral leg in the same group. Blood samples were analyzed for sex hormones, creatine kinase, and lactate dehydrogenase before the tests at the menstrual phase and the preovulatory phase. In addition subjective assessment of muscle soreness was made at each blood sampling. RESULTS Concentric and eccentric peak torque, average power, total work, and endurance ratio at both angular velocities were not significantly different in the two phases of the cycle by paired observation t test for each of the four groups. Except for concentric and eccentric endurance ratios of quadriceps and hamstrings, and concentric peak torque and average power of hamstrings at 180 degrees/sec in Group D, intraclass correlation coefficients of tested variables showed correlations that were moderate to excellent (p < .05) between two phases. In addition, there were no significant correlations between estradiol and the tested variables. Resting serum creatine kinase and lactate dehydrogenase activities and the score of muscle soreness were at the baseline and not significantly different prior to the tests performed at preovulatory and menstrual phases. CONCLUSIONS The results suggest that: (1) reproducibility of isokinetic tests during the menstrual cycle is not influenced by sex hormone fluctuations, particularly estradiol; (2) when compared with the separate test protocol used in this study, the continuous test protocol is more appropriate to measure peak torque, average power, total work, and endurance ratio for both muscle groups of the knee even if the number of contractions is changed. However, these conclusions are specific to sedentary individuals; to make more valid conclusions, further studies with different subject groups are needed.

Eccentric/concentric training of ankle evertor and dorsiflexors in recreational athletes: Muscle latency and strength

The aim of this study was to investigate the effects of a combined eccentric–concentric exercise program of the ankle evertors and dorsiflexors on the latency time of the peroneus longus and tibialis anterior muscles. Twenty‐four healthy male recreational athletes were admitted to this study and were randomly assigned to either the exercise group (n = 12) or the control group (n = 12). Subjects in the exercise group performed an isokinetic exercise program of the ankle evertors and dorsiflexors in a combined eccentric–concentric mode for 3 days per week for 6 weeks. Before and after the exercise program, muscle reaction times of the peroneus longus and tibialis anterior muscles to sudden supinating maneuvers on a tilting platform, and isokinetic strength of the ankle joint musculature were evaluated. The peroneus longus and tibialis anterior reaction times showed significant (P < 0.01–0.05) reductions following six weeks of intervention in the exercise group. Additionally, eccentric peak torques for the ankle evertor and dorsiflexors represented significant (P < 0.05) increases in the exercise group compared with the control group. The results of this study suggest that it is possible to reduce peroneal and anterior tibial reaction times following a six week eccentric/concentric isokinetic training program in healthy ankles.

Eccentric Training Improves Ankle Evertor and Dorsiflexor Strength and Proprioception in Functionally Unstable Ankles.

ObjectiveThe aim of this study was to investigate the effects of a combined eccentric-concentric exercise program of the ankle evertors and dorsiflexors on proprioception in functionally unstable ankles. DesignThirteen male recreational athletes with unilateral functional ankle instability were admitted to this study. The unaffected opposite ankles were used as controls. The functionnaly unstable ankle of the subjects performed an isokinetic exercise program of the ankle evertors and dorsiflexors in a combined eccentric-concentric mode for 3 days per week for 6 wks. Before and after the isokinetic exercise program, active and passive joint position sense and kinesthesia and isokinetic strength of the ankle joint were evaluated. ResultsActive and passive joint position sense error scores for inversion (P < 0.01–0.001) and plantarflexion (P < 0.05–0.001) direction and kinesthesia scores for inversion (P < 0.001) and plantarlexion (P < 0.01) direction showed significant reductions after 6 wks of intervention in the functionnaly unstable ankle. In addition, eccentric peak torques for the ankle evertor and dorsiflexors represented significant (P < 0.001) increases in the functionnaly unstable ankle compared with the control ankle. ConclusionsThe results of this study suggest that it is possible to improve proprioceptive acuity of the ankle joint after a 6-wk eccentric-concentric isokinetic training program in functionally unstable ankles.

Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios.

AIM To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes. METHODS Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension. RESULTS The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05). CONCLUSION According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines.

O-16 Static and dynamic knee stretching: the isokinetic peak torques and electromyographic activities of the contrary muscles

Numerous studies have shown that static stretching compromise a muscle’s ability to produce strength either isometric or isokinetic, and dynamic stretching, on the other hand, may improve muscle strength performance. When the studies were scrutinised, it is obvious that the strength measurements were performed only in the stretched muscles. It is known that during sport activities antagonist muscle co-contractions on the opposite direction are common to prevent overloading to a joint. At the same time, the net external force applied during a movement is proportional to the force produced by the antagonist muscles. Therefore, the aim of this study was to investigate if static and dynamic stretching exercises of the knee muscles (quadriceps and hamstring muscles) have any effects on concentric and eccentric isokinetic peak torques and electromyographic amplitudes (EMG) of the contrary muscles. Twenty healthy male athletes (age between 18-30 years) voluntarily participated in this study. All of the subjects visited the laboratory to complete the following intervention protocol in a randomised order (a-b-c-d-e, b-e-c-d-a, d-c-a-e-b, ……) on 5 separate days; (a) non-stretching (control), (b) static stretching of the quadriceps muscles, (c) static stretching of the hamstring muscles, (d) dynamic stretching of the quadriceps muscles, and (e) dynamic stretching of the hamstring muscles. Static stretching exercises either for the quadriceps or the hamstring muscles were carried out at the standing and sitting positions. Subjects performed four successive repetitions of each stretching exercises for 30 seconds in both stretching positions. Similar to static stretching exercises two different stretching modes were designed for dynamic stretching exercises. Concentric and eccentric isokinetic peak torque for the non-stretched contrary quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities recorded with a portable 8-channel EMG device were measured before the intervention protocol and immediately after. Isokinetic peak torques of the hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching exercises of the quadriceps and hamstring muscles, respectively. Similarly, the EMG activities of the agonist muscles exhibited no significant alterations (p > 0.05) following both stretching exercises of the antagonist muscles. In light of the results of the present study it is possible to state that antagonist stretching exercises either in the static or dynamic modes do not affect the isokinetic peak torques and the EMG activities of the contrary muscles. Acknowledgement The authors would like to express appreciation for the support of the Department of the Scientific Research Projects of Uludag University (Project Number = OUAP(T)−2014/3)

Maximal Cardiorespiratory Capacity in Young Sedentary Male Chronic Smokers

9.01B1.4 9.17B2.05 Work rate, W 242B36 236B26 Heart rate, beats Wmin–1 201B7 199B7 Breathing frequency, min 44B7 46B9 VE(STPD), l Wmin–1 100B9.6 103B8.4 VO2 max, l Wmin–1 2.8B0.3 2.9B0.4 VO2 max, ml Wkg–1 Wmin–1 38.1B4.3 38.6B4.5 Respiratory exchange ratio 1.2B0.1 1.2B0.2 VT, VO2max % 55B13 56B13 VT, liters 2.3B0.3 2.3B0.3 VD/VT 0.16B0.03 0.16B0.06 PETO2, mm Hg 116B6 117B6 PETCO2, mm Hg 46B7 45B7 O2 pulse, ml Wbeat–1 12.2B2.5 12.7B2.0 VE/VO2 35.8B9.1 33.8B8.4 VE/VCO2 28.4B4.2 27.4B5.2