Hakan Gür

Muscle Mass, Isokinetic Torque, and Functional Capacity in Women With Osteoarthritis of the Knee

OBJECTIVES To investigate the relations between cross-sectional area and concentric and eccentric torques in the quadriceps and hamstring muscles and to determine how functional capacity relates to pain, muscle mass, and concentric and eccentric knee torques in women who have bilateral osteoarthritis (OA) of the knee. DESIGN Randomized, descriptive study. SETTING A university exercise physiology laboratory in Turkey. PARTICIPANTS Eighteen women with bilateral knee OA (grades 2 or 3) graded radiographically. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Selected functional tests included the 15-m walk, rising from a chair, descending stairs, and stair climbing. Pain during the functional tests was subjectively measured on an 11-point scale (range, 0-10). Concentric and eccentric torques of the quadriceps and hamstring muscles were measured by isokinetic dynamometry with angular velocities of 60 degrees, 120 degrees, and 180 degrees /s; cross-sectional areas of the quadriceps and hamstring muscles were measured by computed tomography. RESULTS Eccentric torque was significantly (P range, <.05 to.001) greater than concentric torque for the quadriceps (range, 16%-100%) and hamstring (range, 50%-158%) muscles at all angular velocities. Torque-velocity curves for concentric and eccentric contractions were almost identical to those found in healthy young and elderly people. According to r(2) values, cross-sectional area of the quadriceps and hamstring muscles explained 24% to 61% (r(2) range,.24-.61) and 38% to 51% (r(2) range,.38-.51) of the variations in concentric and eccentric peak torques, respectively. Very small to moderate correlations (.01-.75) were observed among torque at any velocity and the variables of functional capacity and pain. For stair-climbing times, the best predictor variable was the eccentric hamstring to concentric quadriceps torque ratio. For stair descending, it was the concentric hamstring to eccentric quadriceps torque ratios. These torque ratios explained 81% (r(2)=.81) and 61% (r(2)=.61) of the variations, respectively. CONCLUSIONS The findings in a patient group with bilateral OA of the knee showed that (1) eccentric torque is greater than concentric torque in knee muscles; (2) the correlation coefficients (r) between concentric and eccentric torques at different velocities (r range,.63-.86), but not between reciprocal torque ratios (r range,.02-.69), are good; (3) cross-sectional area cannot be considered as a single predictor of peak torque for either quadriceps or hamstring muscles; and (4) the variation in descending stairs and stair-climbing capacities can be explained by the reciprocal torque ratios of knee muscles.

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.

Effect of vitamin E supplementation on post-exercise plasma lipid peroxidation and blood antioxidant status in smokers: with special reference to haemoconcentration effect

Abstract The oxidative effects were investigated of exhausting exercise in smokers, and the possible protective role of 400 mg · day−1 vitamin E (Vit E) supplementation over a period of 28 days. The subjects exercised to exhaustion including concentric-eccentric contractions following maximal cycling. The haematocrit and haemoglobin, leucocyte (WBC), plasma lactic acid (La) and malondialdehyde (MDA), erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx), serum Vit E and ceruloplasmin (CER) concentrations were measured pre and post exercise. Supplementation increased Vit E concentrations 28% and 31% in the controls and the smokers, respectively. Cigarette smoking and/or Vit E supplementation did not influence plasma lipid peroxidation or the antioxidant status at rest. Exercise caused significant haemoconcentration in all groups. When the post-exercise concentrations were adjusted for haemoconcentration, a significant elevation in La concentrations due to exercise was observed in all groups. Similarly, there were significant elevations in the adjusted WBC counts in all groups except the Vit E supplemented controls. The MDA concentrations on the other hand, when adjusted for haemoconcentration, did not exhibit any difference due to exercise. Exercise did not affect the GPx and CER activities either, while causing a SOD activity loss in all groups except the Vit E supplemented non-smokers. Serum Vit E concentrations diminished significantly in all groups after exercise. Post-exercise plasma MDA and blood antioxidant concentrations were not altered by smoking. The results would suggest that plasma volume changes should always be taken into account when assessing post-exercise plasma concentrations and that smoking and exercise do not have an additional collective effect on plasma lipid peroxidation and the dose of Vit E administered was insufficient to maintain the serum concentrations after exercise.

Concentric and eccentric isokinetic measurements in knee muscles during the menstrual cycle: A special reference to reciprocal moment ratios

OBJECTIVE To investigate the effects of menstrual cycle on the reliability of concentric (CON) and eccentric (ECC) isokinetic measurements and reciprocal moment ratios in knee muscles. DESIGN Repeated measurements. SETTING A university exercise physiology laboratory. PARTICIPANTS Sixteen healthy sedentary women volunteers, aged 24 to 35 years, who had regular menstrual cycle (ranging from 24 to 32 days). METHODS Subjects were tested at 60 degrees/sec (4 repetitions) and 180 degrees/sec (20 repetitions) of angular velocities for CON and ECC tests at the menstrual (MP, days 1 to 3), follicular (FP, days 7 to 10), and luteal phases (LP, 19 to 21). Blood samples were analyzed for sex hormones at the FP and LP. RESULTS ECC and CON peak torques and total works, and their reciprocal ratios in dominant knee muscles, were not significantly different among the phases by ANOVA. Intraclass correlation coefficients (ICCs) among the phases for peak torque and total work of knee extensors in both angular velocities were in the range of .68 to .91 and .45 to .84 for CON and ECC tests, respectively. However, it was in the range of .03 to .72 and .65 to .94 for CON and ECC tests of knee flexors, respectively. In addition, there were no significant correlations between sex hormones and tested variables. CONCLUSION The results suggest that the phase of the menstrual cycle should not be taken into account in isokinetic measurements.

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.

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)