Acute partial passive stretching increases range of motion and muscle strength.

AIM: The purpose of this study was to investigate the effects of partial passive stretching (PPS) on peak torque (PT) and joint range of motion (ROM) in healthy subjects. METHODS: Twenty-two males (mean age 20.4±1.0 yrs, height 181.1±4.2 cm and weight 75.8±6.8 kg) participated in the study. Quadriceps and hamstrings PT at different angular velocities was obtained on an isokinetic dynamometer. Standing leg method hop was tested for the stretched and unstretched leg. Each subject performed PPS for 20 seconds. The stretching procedure was repeated 5 times for each muscle group. The whole stretching program lasted for 6 minutes and 20 seconds followed by 5 seconds resting period. RESULTS: Directly after the stretching procedure significant increases were observed of PT in quadriceps and hamstrings, however, only at 300o.s⁻¹ (P<0.05). Joint ROM was increased in all subjects (P<0.05). The distance in single length hop was increased significantly in the stretched leg following stretching (P<0.05). No changes were observed in the unstretched leg. CONCLUSION: Our results indicated that the PPS altered ROM, maximal concentric isokinetic strength at high angle velocities and single length hop only for the stretched leg. These findings suggest that PPS may be an effective technique for enhancing muscle performance.

"Living high - training low" vs. "living high - training high": erythropoietic responses and performance of adolescent cross-country skiers.

AIM: To determine and compare the erythropoietic response and exercise performance of adolescent cross-country skiers, as a result of "living high-training high" (HH) and "living high-training low" (HL). METHODS: Nine female and six male adolescent cross-country skiers volunteered to participate in separate trials. In the first trial (HH), the skiers lived and trained for 21 days at 1550-2050 m, while in the second trial (HL) they trained near sea level (450-500 m) but resided at 1550 m. All participants underwent maximal cycle ergometer tests for the determination of VO2max and cardiorespiratory parameters via an open circuit system at sea level before ascent to altitude, and 1-2 days after descent from altitude. Blood samples were drawn prior to and immediately after maximal cycle exercise testing, at sea level prior to ascent, on days 1 (D1) and 21 (D21) at altitude (1740 m), and 1-2 days post-altitude, for the determination of serum erythropoietin (EPO) concentration, haemoglobin (Hb), hematocrit (Ht), and red blood cell (RBC) volume. RESULTS: The results showed that both boys and girls cross-country skiers, significantly improved their sea level VO2max after 21 days of living at moderate altitude and training near sea level. CONCLUSION: The present study demonstrates that living at moderate altitude, 1550-2050 m and training low, near sea level (450-500 m) significantly increases VO2max and RBC mass for both boys and girls. Results indicate that applying the training concept "living high - training low" in adolescent athletes may improve their endurance performance.

Deltoid muscle characteristics in wrestlers.

The purpose of the present study was to investigate the deltoid muscle characteristics of wrestlers. Nine Greco-Roman competitive male wrestlers (mean age 20.1+/-2.7 yrs, height 175+/-0.6 cm, weight 83.2+/-12.5 kg, years of training 7.6+/-2.7 yrs) participated in this study. Six male healthy sedentary students (mean age 21.2+/-0.9 yrs, height 180+/-0.3 cm, weight 80.1+/-9.4 kg) served as controls. Muscle fibre distribution, cross-sectional area (CSA), as well as satellite cells, myonuclei and capillary density per muscle fibre area were determined by immunohistochemistry. Myosin heavy chain MHC isoform composition of single fibres was determined with protein electrophoresis. Immunohistochemical analysis showed that muscle fibre distribution of the MHC I and IIA were significantly higher in wrestlers than in controls (p<0.05). Electrophoretic analysis of single fibres revealed a significantly higher proportion of fibres containing MHC I and IIC in wrestlers (p<0.05). The mean CSA of type IIA fibres and the number of myonuclei per type II was significantly higher in wrestlers (p<0.05). We also found that the number of satellite cells was 2.5 fold higher in wrestlers than in the control group. This study suggests that the observed muscle fibre profile in the deltoid of wrestlers may represent an adaptation based on the specific mechanical and biochemical demands of the long-term training in Greco-Roman wrestling.

Deltoid muscle fiber characteristics in adolescent and adult wrestlers.

AIM: The aim of the present study was to examine the adaptation of myosin heavy chain (MHC) isoforms, capillary density and fiber cross sectional area (CSA) of deltoid muscle in adolescent and adult elite Greco-Roman wrestlers. METHODS: Eighteen Greco-Roman wrestlers were divided into two groups: adolescents included 10 athletes (group A) between 14-18 years of age (15.4+/-1.3 yrs) and adults included 8 athletes (group B) between 20-27 years (23.5+/-2.6 yrs). Histochemical analyses were used to determine the muscle fiber type distribution and the muscle fiber cross sectional area. MHC isoform composition was determined with protein electrophoresis, while capillary density (capillary to fiber ratio and capillaries per mm2) analysis was performed with a-amylase Periodic and Schiff staining. RESULTS: Adolescents demonstrated a significantly higher percentage of type I fibers (P<0.05) and type I fiber area (P<0.05) compared to the adults. The percentage of type IIa fiber area were significantly higher in adult wrestlers (P<0.05). MHC I isoforms was significantly higher in adolescents (P<0.05), whereas the MHC isoforms of IIa and IIx did not differ between groups. The capillary density (mm2) were significantly higher (P<0.05) in adolescents compared to adults. CONCLUSION: Our findings suggest that the observed muscle fiber profile in the deltoid muscle of wrestlers may represent an adaptation based on the mechanical and biochemical demands of the long-term training. Such adaptations are linked to the specific characteristics of the training program, the level and the previous training experience of the wrestlers.

Specific inspiratory muscle training does not improve performance or VO2max levels in well trained rowers.

AIM: The purpose of this study was to examine the effects of specific inspiratory muscle training (IMT) on inspiratory muscle strength, maximal oxygen uptake (VO2max), maximal lactate accumulation (Lmax), dyspnea sensation and rowing performance in rowers. METHODS: Ninteen well-trained rowers were divided into two groups: IMT (T) and control (C). The T group, in addition to their daily rowing practice, performed IMT by means of a threshold inspiratory muscle trainer for approximately 0.5h.d(-1), 5 times a week for 6 weeks. The C group participated only in their regular daily rowing training. Prior to the initiation and at the completion of the 6-week IMT program, both groups underwent an incremental treadmill run test to determine VO2max. Maximum inspiratory mouth pressure (PImax) was measured at rest and following the VO2max test. On a separate occasion, rowing performance was evaluated by a 2000 m all-out effort on a rowing ergometer. Dyspnea sensation was assessed by a modified Borg scale and Lmax was measured by an enzymatic method. RESULTS: Six weeks of IMT significantly (P < 0.05) increased resting PImax. Moreover, inspiratory muscle training increased PImax following the VO2max test in the T group. In contrast, no changes in PImax were observed in the C group during the 6-week period. No significant differences were observed between pre- and post-test values in VO2max, dyspnea sensation, Lmax, and 2000 m race time in both groups. CONCLUSION: In conclusion, six weeks of IMT increases inspiratory muscle strength by approximately 28% in highly trained rowers. However, this increase in inspiratory muscle strength does not appear to improve VO2max, dyspnea sensation during exercise, or rowing performance in well-trained rowers.

The response of muscle interstitial F2-isoprostane (8-ISO-PGF2alpha) during dynamic muscle contractions in humans.

8-Iso-prostaglandin F2alpha (8-iso-PGF2alpha) is a characteristic F2-isoprostane which is produced in humans via a free radical-catalysed lipid peroxidation mechanism of arachidonic acid, independent of the cycloxygenase pathway. The measurement of the plasma levels of 8-iso-PGF2alpha was shown to be the most reliable biochemical index of oxidant stress status in the human body. However, there is no reference in literature of local muscle interstitial 8-iso-PGF2alpha production during dynamic muscle contractions. The aim of the present study was to evaluate the response of 8-iso-PGF2alpha during intensive exercise with a cycle ergometer. Two microdialysis probes with CMA-60 microdialysis catheters were inserted into the vastus lateralis muscle of the right leg of six healthy male volunteers. After insertion, these microdialysis probes were attached to a perfusion pump that perfused ringer acetate solution at a rate of 0.3 microl/min. The dialysate fluid samples were collected: (a) during a 30 min rest period and (b) during a 30 min period of dynamic exercise with a cycle ergometer at 150 Watts. Our measurements showed that the levels of 8-iso-PGF2alpha in the interstitial fluid (IF) of the vastus lateralis muscle increase significantly during exercise (from 113.5 +/- 30.2 to 329.9 +/- 69.8 pg/ml, P = 0.05). In conclusion, dynamic muscle exercise produces a local increase of the IF levels of 8-iso-PGF2alpha due to local peroxidation injury of the contractive muscle. The microdialysis method is widely applied, easily repeated and it could contribute in evaluating the local lipid muscle peroxidation during intensive exercise.

The response of muscle interstitial prostaglandin E(2)(PGE(2)), prostacyclin I(2)(PGI(2)) and thromboxane A(2)(TXA(2)) levels during incremental dynamic exercise in humans determined by in vivo microdialysis.

UNLABELLED: The microdialysis in vivo technique allows the isolation, purification and quantitative determination of bioactive molecules with low molecular weight (<20.000 Da) from interstitial fluid (IF) of the muscles. PGE(2)and PGI(2)are vasodilator local hormones, while the TXA(2)is a vasoconstrictor. PGI(2)and TXA(2)are unstable and convert to stable products 6-keto-PGF(1a)and TXB(2), respectively. The purpose of this study was to evaluate the response of PGE(2), PGI(2)and TXA(2)in the IF of human muscle (vastus lateralis) during dynamic exercise with a cycle ergometer. In this study two microdialysis probes were inserted with CMA-60 microdialysis catheters into the vastus lateralis muscle of the right leg of eight healthy volunteers aged 24.1+/-2.1 years, height 177.5+/-1.5 cm and body weight 78.1+/-2.4 kg. After insertion the microdialysis probes perfused at a rate of 3.0 microl/min with Ringer acetate solution. The dialysate fluid was collected a) during the 30' rest period, b) during the 30' exercise period at 100 watts, c) during the 30' exercise period at 150 watts and d) during the 30' rest period after exercise. Our measurements (by the RIA method) showed that the levels of PGE(2)and 6-keto-PGF(1a)in the I.F. of the vastus lateralis muscle increased significantly, while there was a significant decrease in TXB(2)during exercise. The changes in the above biomolecules were increased proportionately with the strain of the subject's muscle. CONCLUSION: Dynamic exercise of the muscles produces a local increase of the vasodilators PGE(2)and PGI(2)while the vasoconstrictor TXA(2)is reduced in the IF of the muscles. This is further evidence that exercise induces propitious biochemical changes. Furthermore, the muscle production of arachidonic acid metabolites during exercise depends on the intensity of the exercise.

Peak torque of quadriceps and hamstring muscles in basketball and soccer players of different divisions.

Basketball and soccer are two games with different training and playing procedures. The purpose of this study was to examine the maximal voluntary peak torques of the quadriceps and hamstring muscles, and the torque ratio between these muscle groups in basketball players (n = 61) and soccer players (n = 51) participating in teams of different divisions. Isokinetic peak torques were measured using the Cybex II isokinetic dynamometer at 60 and 180 degrees.s-1. Basketball players of the national team produced higher peak torque values of quadriceps muscles than the other basketball players of different divisions (p < 0.05 to p < 0.001). Hamstring peak torques of the national basketball team were significantly higher the only velocities measured compared with the players from division II and IV (p < 0.05). Peak torque values of quadriceps muscles relative to body weight were significantly higher in the national basketball team compared with basketball players from division I. No significant differences were found in peak torque values of quadriceps and hamstring muscles within the different basketball and soccer divisions. Peak torque expressed in absolute terms was significantly higher in basketball players than in soccer players (p < 0.05 to p < 0.001). However, these differences were not significant when the strength of quadriceps and hamstring muscles was expressed relative to body weight. The H/Q ratio did not differ either ditto among the different divisions of basketball and soccer players. Based on the data obtained in this study, we concluded that the subjects' body weight have a decisive effect on the production of peak torque values of quadriceps and hamstring muscles in basketball and soccer players. Furthermore that the playing in different divisions, as well as participating in different sports, i.e. basketball or soccer, have surprisingly small effects on the peak isokinetic torque production of the quadriceps and hamstring muscles.

Cardiorespiratory and metabolic responses during straight and bent knee cycling.

BACKGROUND: This study examined the influence of knee angle on the cardiorespiratory system loading during submaximal and maximal stationary cycle ergometry. METHODS: Experimental design and participants: eighteen untrained women (age: 21+/-1.88 years, weight: 57+/-5.75 kg, height: 165+/-5.03 cm, values are mean+/-SD) volunteered as subjects and underwent two-cycle ergometer incremental (Jaeger ER900) tests: 1) straight knee (180 degrees), 2) bent knee (140 degrees). MEASURES: oxygen uptake (VO2), ventilation (VE) and respiratory exchange ratio (RER) were measured continuously during each test using an open circuit spirometry and blood lactate concentration was determined by means of an enzymatic method. RESULTS: Comparing cycling with "straight knee" to cycling with "bent knee" at 50 W, heart rate (HR), V(E) and VO2 were significantly higher (10.6%, 12.5%, 17.8%). At 100 W, blood lactate was significantly lower (10.8%) while VO2 and RER was higher (5.5%, 7.1%). During maximal exercise, the total exercise time was significantly longer (11.2%) and VE, VO2 and HR were significantly higher during cycling with "straight knee" compared to cycling with "bent knee". No significant difference in peak lactate was evident between the two sitting positions. CONCLUSIONS: The results of this study indicate that cycling with bent knee requires lower oxygen uptake while pedaling with straight knee is the only way to reach VO2max during cycle testing, since the cardiorespiratory system is fully taxed.

Measurement of range of motion in individuals with mental retardation and with or without Down syndrome.

The purpose of this study was to assess differences in variability of three joints' range of motion in the lower extremity among individuals with Down syndrome, mentally retarded individuals without Down syndrome, and sedentary subjects without mental retardation (ns = 13, 25, and 30, respectively). Range of motion for hip and knee flexion was obtained using a Myrin goniometer. For hip abduction the range of motion was obtained using a double protractor goniometer (Brodin type). Three test repetitions were carried out, and the greatest value was recorded. As no significant differences were found between left and right sides for each motion, the average was used to represent the range of motion. The Down syndrome group had significantly higher mean range of motion in hip flexion than the mentally retarded group. No significant differences in mean range of motion were found between Down syndrome and sedentary groups, but a significant difference was observed between the control and mentally retarded groups. In hip abduction, the Down syndrome group showed significantly higher mean range of motion than the control and mentally retarded groups. The control group had significantly a higher mean range of motion than the mentally retarded group. No significant differences were found in knee flexion between the two mentally disabled groups, but significant differences in mean range of motion were found between each of the two groups of mentally retarded individuals and the control group. Because differences exist in mean range of motion between the two mentally disabled groups, individualized and differentiated training programs to improve flexibility must be designed based on the type of handicap.

Isokinetic knee muscle strength of individuals with mental retardation, a comparative study.

The purpose of this study was to assess differences in isokinetic muscle torque in the knee among mentally retarded individuals with Down syndrome, mentally retarded individuals without Down syndrome, and sedentary subjects without mental retardation (ns of 7, 8, and 12, respectively). Subjects performed strength tests to knee extension and flexion on a Cybex II isokinetic dynamometer. The measure was peak torque at angular velocities of 60, 120, and 300 degrees/sec. For the Mentally Retarded subjects with and without Down syndrome, the test was performed on two separate days 24 hr. apart. For Sedentary subjects, testing was performed on one day. Their scores indicated significantly higher values of torque than the two other groups. Also, subjects with Down syndrome had inferior muscle torque of lower extremities than peers in the Mentally Retarded Group.

Does the intensity of an exercise programme modulate body composition changes?

Exercise training is a useful component of weight maintenance programmes. Although energy expenditure, not intensity or duration, seems to determine the amount of weight loss attributable to exercise, it is not clear whether changes in the components of body mass are also insensitive to these parameters. Thus, the aim of the present study was to compare the effect of two isoenergetic exercise training programmes, one of low and one of high intensity, on body composition. Fourteen healthy premenopausal untrained women were divided into two equivalent groups, which exercised on treadmill at 45 or 72 % of V(O2max) four times a week for three months, spending 1548 kJ (370 kcal) per exercise session. No dietary intervention was applied. Body mass decreased significantly in both groups but more in the low-intensity than the high-intensity group (by mean +/- SD, 3.3 +/- 1.3 vs. 1.9 +/- 0.9 kg, p = 0.032). The decrease in fat mass was significant in both groups (3.1 +/- 1.2 vs. 2.4 +/- 1.5 kg, respectively) but not significantly different between them. Fat-free mass did not change significantly in either group, although the difference between groups tended to be significant (decrease by 0.2 +/- 0.7 kg in the low-intensity group vs. increase by 0.5 +/- 0.6 kg in the high-intensity group, p = 0.058). In conclusion, exercise training at 45 % of V(O2max) without dietary restriction produced a higher weight loss than at 72 % of V(O2max), whereas the higher intensity tended to maintain fat-free mass, possibly, in part, through the smaller weight loss. Thus, both programmes may prove useful in eliciting favourable changes depending on which target (weight loss or maintenance of fat-free mass) is of higher priority.

Atrial natriuretic factor responses to submaximal and maximal exercise.

The aim of this study was to evaluate and compare the plasma concentration of atrial natriuretic factor (ANF), K+, Na+, blood lactate, heart rate, and blood pressure in moderately trained women. Ten healthy women were studied on a cycle ergometer during 20 min of constant submaximal and maximal exercise, as well as during recovery. The ANF concentration was determined by radioimmunoassay. The results show that, except for Na+, all the other variables increased significantly with an increase in the duration and intensity of the exercise (P < 0.05, P < 0.001). In recovery, the values fell (P < 0.01, P < 0.001). Submaximal and maximal exercise both cause increases in ANF and this increase is due to the duration and intensity of exercise. However, maximal exercise, rather than submaximal exercise, is the major stimulus for the concentration of plasma ANF. ANF concentration may be a useful test for evaluating the releasing function of ANF in the heart.