Effects of Muscle Architecture on Eccentric Exercise Induced Muscle Damage Responses.

There is a need to investigate the role of muscle architecture on muscle damage responses induced by exercise. The aim of this study was to determine the effect of muscle architecture and muscle length on eccentric exercise-induced muscle damage responses. Eccentric exercise-induced muscle damage was performed randomly to the elbow flexor (EF), knee extensor (KE), and knee flexor (KF) muscle groups with two week intervals in 12 sedentary male subjects. Before and after each eccentric exercise (immediately after, on the 1st, 2nd, 3rd, and 7th days) range of motion, delayed onset muscle soreness, creatine kinase activity, myoglobin concentration and isometric peak torque in short and long muscle positions were evaluated. Furthermore, muscle volume and pennation angle of each muscle group was evaluated before initiating the eccentric exercise protocol. Pennation angle and muscle volume was significantly higher and the workload per unit muscle volume was significantly lower in the KE muscles compared with the KF and EF muscles (p < 0.01). EF muscles showed significantly higher pain levels at post-exercise days 1 and 3 compared with the KE (p < 0.01-0.001) and KF (p < 0.01) muscles. The deficits in range of motion were higher in the EF muscles compared to the KE and KF muscles immediately after (day 0, p < 0.01), day 1 (p < 0.05-0.01), and day 3 (p < 0.05) evaluations. The EF muscles represented significantly greater increases in CK and Mb levels at day 1, 3, and 7 than the KE muscles (p < 0.05-0.01). The CK and Mb levels were also significantly higher in the KF muscles compared with the KE muscles (p < 0.05, p < 0.01 respectively). The KF and EF muscles represented higher isometric peak torque deficits in all the post-exercise evaluations at muscle short position (p < 0.05-0.001) compared with the KE muscle after eccentric exercise. Isometric peak torque deficits in muscle lengthened position was significantly higher in EF in all the post-exercise evaluations compared with the KE muscle (p < 0.05-0.01). According to the results of this study it can be concluded that muscle structural differences may be one of the responsible factors for the different muscle damage responses following eccentric exercise in various muscle groups.

Dynamic stretching does not affect peroneal and tibial muscle reaction properties.

OBJECTIVES: This study aims to investigate acute and chronic effects of dynamic stretching on peroneal and tibialis anterior reaction properties. PATIENTS AND METHODS: Between September 2015 and June 2017, a total of 21 male athletes (mean age 22.6 years; range, 20 to 30 years) were included in this study. All participants were randomly divided into two groups as dynamic stretching group (n=11) and control group (n=10). The participants in the dynamic stretching group performed stretching exercises for the ankle evertor and dorsiflexor muscles five days a week for six weeks. Peroneal and tibial muscle reaction properties were evaluated at baseline (two times for acute effect) and at the end of the intervention. Electromyographic activity parameters including reaction time, reaction duration, and reaction magnitude of the muscles were measured using an ankle supination tilting platform. There were four different supination conditions: (i) ankle neutral, 15° inversion (0015), (ii) ankle neutral, 30° inversion (0030), (iii) ankle 20° plantarflexion, 15° inversion (2015), and (iv) ankle 20° plantarflexion, 30° inversion (2030). RESULTS: There were no significant differences in acute and chronic effects of dynamic stretching exercises for peroneal and tibial muscle reaction time, reaction duration, and muscle activity in four positions on the ankle inversion simulation platform (p>0.05). CONCLUSION: Our study results suggest that dynamic stretching exercises have no positive or negative effects on muscle reaction properties and on the possible risk of ankle sprain during sudden ankle inversion. Dynamic stretching exercises may still be preferred for sports where strength and force effects are important.

The Effect of Static Stretching of Peroneal and Tibialis Anterior Muscles on Reaction Time: A Randomized Controlled Study.

OBJECTIVE: The aim of this study was to investigate the acute and chronic effects of static stretching on peroneal and tibialis anterior reaction characteristics. DESIGN: All 23 participants who volunteered for this study were randomly divided into static (n = 12) and control (n = 11) groups. The subjects in the static stretching group performed stretching exercises for the ankle evertor and dorsiflexor muscles 5 days a week for 6 wks. Peroneal and tibialis anterior muscle reaction characteristics were evaluated at the beginning (2 times for acute effect) and end of this period. Electromyographic activity parameters of the muscles were measured using an ankle inversion tilting platform that simulated a sudden ankle inversion. The following were the four different ankle inversion conditions: (a) ankle-neutral, 15-degree inversion; (b) ankle-neutral, 30-degree inversion; (c) ankle-20-degree plantarflexion, 15-degree inversion; and (d) ankle-20-degree plantarflexion, 30-degree inversion. RESULTS: Either in terms of acute or chronic effects, no significant differences were found after static stretching exercises for peroneal and tibialis anterior muscle reaction time, reaction duration, and muscle activity evaluated in four positions on the ankle inversion simulation platform (P > 0.05). CONCLUSIONS: In light of these results, it is possible to state that the short duration of static stretching exercises can still be applied before sports activities.

Effect of Upper-Extremity Strengthening Exercises on the Lumbar Strength, Disability and Pain of Patients with Chronic Low Back Pain: A Randomized Controlled Study.

The present study aimed to analyze the impacts of a low back rehabilitation program accompanied with neck, shoulder and upper back exercises on pain, disability, and physical characteristics of patients with chronic low back pain. Twenty sedentary male patients with chronic low back pain participated in the study on a voluntary basis. The patients were randomly allocated into two groups: a conventional low back exercise group (CE) and a supported exercise group (SE; CE plus upper back, neck, and shoulder exercises). The Modified Oswestry Disability Questionnaire (MODQ) was used to evaluate the disability status and the Visual Analog Scale (VAS) was used to identify the pain states of the patients. In addition, neck, lumbar and shoulder isokinetic and isometric strengths of the patients were evaluated. The CE group performed lumbar stretching, mobilization and stabilization exercises in addition to low-back and abdominal isometric and concentric strengthening exercises. The SE group performed static stretching and isotonic exercises for the neck, upper-back, and shoulder muscles, in addition to the exercises performed in CE group. The exercises were implemented 3 days a week for 6 weeks in both groups. Following the 6-week exercise periods in both groups, statistically significant (p < 0.01) improvements were observed in the patients' levels of pain and the scores of MODQ reflecting an easing of disability. With respect to the levels of pain and disability, the improvements observed in the SE group was significantly (p < 0.01) greater than the improvement observed in the CE group. Based on the findings of this study, we can conclude that a low back exercise program used in combination with neck, shoulder and upper back exercises reduces the level of pain and disability in patients with chronic low back pain more prominently than conventional low back exercises.

Effects of Static and Dynamic Stretching on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist Muscles.

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 antagonist 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 in a randomized order 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 antagonist quadriceps or hamstring muscles at angular velocities of 60°/sec and 240°/sec and their concurrent electromyographic (EMG) activities were measured before and immediately after the intervention. Isokinetic peak torques of the non-stretched agonist hamstring and quadriceps muscles did not represent any significant (p > 0.05) differences following static and dynamic stretching of the antagonist 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. According to 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 non-stretched agonist quadriceps or hamstring muscles.

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

OBJECTIVE: The 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. DESIGN: Thirteen 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. RESULTS: Active 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. CONCLUSIONS: The 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.

Early versus late start of isokinetic hamstring-strengthening exercise after anterior cruciate ligament reconstruction with patellar tendon graft.

BACKGROUND: 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 degrees 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.

Difference in the magnitude of muscle damage between elbow flexors and knee extensors eccentric exercises.

The aim of this study was to investigate the difference in the magnitude of muscle damage between maximal eccentric exercises of the elbow flexors (EF) and knee extensors (KE). Twelve sedentary male volunteers participated in the study. Range of motion (ROM), isometric peak torque (IPT), delayed onset of muscle soreness (DOMS), creatine kinase activity (CK), and myoglobin concentration (Mb) were evaluated before, immediately after, and on the 1(st) , 2(nd), 3(rd) , and 7(th) days following exercise. Total work (TW) during exercises was recorded and corrected by muscle volume (TWc). TWc was greater (p < 0.01) for EF [24 (2) joule·cm-3] than for KE [7 (0.4) joule·cm(-3)]. Increases in CK on the 2(nd) , 3(rd) , and 7(th) days (p < 0.01) and increases in Mb on the 1(st) , 2(nd) , 3(rd) , and 7(th) days were significantly (p<0.01) larger for EF than for KE. The decline in IPT was greater (p < 0.05- 0.01) for EF at all test occasions compared with KE. The results of this study demonstrate that the magnitude of muscle damage is greater and the recovery is slower following maximal eccentric exercise of the EF than of the KE for sedentary males. Key pointsThe magnitude of muscle damage is greater and the recovery is slower following maximal eccentric exercise of the EF than of the KE for sedentary males.This may be because of the higher total eccentric work per muscle unit in elbow flexors.

Myocardial performance and aortic elastic properties in elite basketball and soccer players: relationship with aerobic and anaerobic capacity.

The aims of the present study were to examine the myocardial performance index and aortic elastic properties of athletes engaged in ball sports and to determine their relationships with aerobic and anaerobic characteristics. Standard M-mode and Doppler echocardiography, maximal oxygen uptake and 30 sec Wingate tests were performed for 32 elite male athletes (12 basketball and 20 soccer players) and 12 healthy sedentary volunteers. Data were analyzed by ANOVA and partial correlation coefficient tests. Absolute values of left ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole were significantly (p < 0.05-0.01) greater in athletes than in controls. The left ventricular internal diameter corrected by body surface area was also greater (p < 0.05-0.01) in the athletes compared with the controls. Absolute and body surface area corrected left ventricular mass were significantly greater (p < 0.05-0.001) in athletes than in controls. Isovolumetric relaxation time was higher (p < 0.01) in soccer players than in controls. There were no significant differences among the groups for myocardial performance index and aortic elastic properties. Left ventricular mass index was poorly correlated (p < 0.01) with VO2max (r = 0.410), peak power (r = 0.439) and average power (r = 0.464) in the athletes. Poor correlations (r = 0.333-0.350, p < 0.05) were also observed between aortic elastic properties and average power in athletes. Myocardial performance index and aortic elastic properties are not different in athletes involved in this study compared with sedentary subjects. Aerobic and anaerobic capacities of the athletes used in this study are poorly explained by these resting echocardiographic findings. Key PointsLeft ventricular internal diameter, left ventricular posterior wall and interventricular septum thicknesses in diastole, and left ventricular mass were significantly greater in athletes than in controls.There were no remarkable differences in Doppler velocities and time intervals between athletes and controls.Myocardial performance index and aortic elastic properties are not different in athletes compared with sedentary subjects.Aerobic and anaerobic parameters of athletes are poorly explained by resting echocardiographic characteristics.VO2max and anaerobic power indices are variables that better determines left ventricular mass developed in ball sport specific training.

[The role of aerobic exercise following myocardial infarction]. / Miyokard Infarktüsü Sonrasi Aerobik Egzersizin Rolü

Aerobic exercise training has an important role within the cardiac rehabilitation program. An exercise test performed in the early period after myocardial infarction (MI) allows determining early the functional status and the risk factors of the patients and can accelerate their return to their occupational life. Patients can get back faster and safely to their active lifestyle following MI with exercises carried out at least 3 days per week, for 20 to 60 minutes and at intensities between 40% to 85% of VO2max. These exercises may concern the lower extremity like walking or running, upper extremity like arm cycle ergometer or combinations of these like rowing or swimming. Regular aerobic exercises increase the functional capacity and parasympathetic tone, and these together lead to an improvement in cardiovascular autonomic control. As a result, frequency of coronary artery disease and other cardiovascular diseases declines to an important extent. Studies conducted in humans and animals have shown contradictory outcomes about left ventricular remodelling. General opinion is that aerobic exercise has no favourable effect on ventricular remodelling.

Concentric versus combined concentric-eccentric isokinetic training: effects on functional capacity and symptoms in patients with osteoarthrosis of the knee.

OBJECTIVE: To compare the effects of concentric and coupled concentric-eccentric isokinetic resistance training on functional capacity and symptoms of patients with osteoarthrosis (OA) of both knees. DESIGN: Repeated measures. SETTING: A university exercise physiology laboratory. PARTICIPANTS: Twenty-three volunteers, ages 41 to 75 years. Patients were randomly assigned to 3 groups: concentric (CON, n = 9), concentric-eccentric (CON-ECC, n = 8), and nontreatment (NONTX, n = 6). INTERVENTIONS: The CON group performed 12 concentric contractions of each knee extensor and flexor muscles; the CON-ECC group performed 6 concentric and 6 eccentric contractions of each knee muscle group by using a spectrum of angular velocities ranging from 30 degrees/s to 180 degrees/s with 30 degrees/s intervals, for both sides, 3 days a week for 8 weeks. MAIN OUTCOME MEASURES: Functional capacity (rising from a chair, walking, stair climbing and descending) and pain during rest and activities, peak torque, and cross-sectional area (CSA) of knee muscle groups of subjects were tested before and after training. RESULTS: Both training groups showed marked decreases (P <.001) in pain scores and increases (P <.001) in functional capacity together with increases (P <.05--.01) in peak torque and CSA of knee muscles. However, the NONTX group did not display these marked changes after the 8-week period. The results also indicated that concentric-eccentric training has a greater influence on functional capacity, especially stair climbing and descending, than that of concentric training when compared with NONTX group; however, the improvements in pain measurements were better in the CON group compared with the CON-ECC group after the training. CONCLUSIONS: The results suggest that with the isokinetic resistance training used in this study, it is possible to improve functional capacity and decrease pain in patients with OA of the knee. The results also showed that extensive training involving a high number of repetitions and eccentric contractions was safe, effective, and well tolerated for the patients with knee OA.

Avulsion of the ischial tuberosity in a young soccer player: six years follow-up.

In this case a seventeen-years-old male soccer player, who sustained an injury while playing football, diagnosed as ischial tuberosity avulsion was reported. Following six-months of a conservative rehabilitation program, the athlete returned to his sports' activities. Six years along he had no complaints and his athletic performance was not deteriorated. In this case report diagnosis, treatment and six-years follow-up results were discussed.