GROUND REACTION FORCES IN NORDIC WALKING AND WALKING

Nordic Walking as an established endurance sports showed a higher cardiovascular load compared to normal walking caused by the additional use of poles (Butts et al. 1995; Rodgers et al. 1995; Jordan et al. 2001). There is still a lack of knowledge regarding the joint load. A reduction up to 30% based on the use of poles is often described but the evidence is missing. The objective of the given study was to examine the load on lower limbs using biomechanical parameters comparing walking [W] and nordic walking[NW]

CHANGES IN POSTURAL CONTROL AND PROPRIOCEPTIVE CAPABILITIES AFTER KUNG FU TRAINING PROGRAM IN LOW BACK PAIN PATIENTS

Low Back pain is often associated with reduced kinesthetic perception of the lower back and may result in early annuity or incapacitation for work. Special low back training programs can improve kinesthetic capabilities of low back pain patients. The effect of Kung Fu training has not been previously shown to be of benefit to sensorimotor control. Thirty-five volunteers (31.2 ± 6.3 years) were divided into two groups: Kung Fu exercise group (test group; with low back pain; n=23; training 2.9 ±2.3 h/week), control group (with low back pain; n=12; 34.1 ±4.2 years; training 0.25 ±0.8 h/week). During an active reproduction test, subjects performed the following trunk positions in random order: flexion [A (0°-20'), lateral flexion [B (0°-20')]. Using a 3D-ultrasound motion analysis system the repositioning error was calculated from the given target position to the subject perceived target position. Furthermore postural balance on a force plate and isometric force of back muscles were measured before and after an 8 week training period inclUding 16 training sessions. The results showed a decreasing repositioning error after the training period for the Kung Fu training group, in addition to an improvement in postural balance, whereas no significant changes in isometric strength could be demonstrated

SENSORIMOTOR ASPECTS OF THE SPINE IN ATHLETES AND NON-ATHLETES

Deficits in proprioceptive capabilities are often associated with the occurrence of low back pain as seen in tests involving exact position reproduction. The degree to which athletic activity can improve kinesthetic sensibility of the spine has not been satisfactorily determined previously. Twenty-seven volunteers (30.4 ±4.4 years) were divided into two groups: athletes (n=18; training 5.7 ±3.8 h/week) and non-athletes (n=9). During an active reproduction test, subjects performed the following trunk positions in random order: flexion [A(10°-20°), B(40°-60°), C(80°-90°)], lateral flexion [A(0°-20°), B(20°-45°)], and axial rotation [A(0°-20°), B(20°-45°)].Using a 3D-ultrasound motion analysis system the variability of the given angle was recorded for each trial. A large variation was generally demonstrated in the measured values. Regarding the accurate reproduction of a given angle, the athlete group showed less discrepancy with a smaller standard deviation than the non-athlete group. The results point to superior kinesthetic abilities in the athlete group and the possibility of improving proprioceptive functions with training

INFLUENCE OF KNEE BANDAGES ON EMG PATTERNS OF THE QUADRICEPS MUSCLE DURING ‘DROP JUMPS’

INTRODUCTION: The therapeutic management of knee injuries is still a central topic in the field of sports traumatology. Different therapeutic concepts and functional training, as well as proprioceptive stimulation with external devices, are discussed for optimized active muscular stabilization. The purpose of this study was to evaluate the influence of knee bandages on the electromyogram (EMG) patterns of the quadriceps muscle in performing ‘drop jumps’ from various heights. METHODS: Twelve healthy male volunteers (mean age: 24.7±2.8 years; mean weight: 78.3±4.0 kg; mean height: 184.5 ±6.2 cm) with a regular training frequency of at least 5.7 hours a week were tested in a randomized order, performing four ‘drop jumps’ from each of five heights (16cm, 32cm, 48cm, 64cm; 80 cm) using two types of knee bandages (‘Kasseler-patellar-tendon bandage’; ‘Genu-plus bandage’), as well as without a bandage. Muscular activation of the knee-stabilizing muscles was recorded by an 8-channel EMG-System with surface electrodes. For the assignment of ground reaction forces we used a Kistler platform. Mean values of all data regarding bandage type and drop height were calculated; statistical evaluation for significant differences was performed at the 95% confidence level using SPSS statistics software. RESULTS: Our results showed a significantly shorter activation latency of the different parts of the quadriceps muscle (m. rectus femoris; m. vastus lateralis; m. vastus medialis) with increasing jumping height using a knee bandage compared to drop jumps without a knee bandage. [ CONCLUSION: With regard to the influence of knee bandages on sensomotoric functions, it seems to be profitable to use such proprioceptive stimulation for optimizing active muscular stabilization

Longer Work/Rest Intervals During High-Intensity Interval Training (HIIT) Lead to Elevated Levels of miR-222 and miR-29c

Aim: MicroRNA-222 (miR-222) and miR-29c have been identified as important modulators of cardiac growth and may protect against pathological cardiac remodeling. miR-222 and -29c may thus serve as functional biomarkers for exercise-induced cardiac adaptations. This investigation compared the effect of two workload-matched high-intensity interval training (HIIT) protocols with different recovery periods on miR-222 and -29c levels.Methods: Sixty-three moderately trained females and males (22.0 ± 1.7 years) fulfilled the eligibility criteria and were randomized into two HIIT groups using sex and exercise capacity. During a controlled 4-week intervention (two sessions/week) a 4 × 30 HIIT group performed 4 × 30 s runs (all-out, 30 s active recovery) and a 8 × 15 HIIT group performed 8 × 15 s runs (all-out, 15 s active recovery). miR-222 and -29c as well as transforming growth factor-beta1 (TGF-beta1) mRNA levels were determined during high-intensity running as well as aerobic exercise using capillary blood from earlobes. Performance parameters were assessed using an incremental continuous running test (ICRT) protocol with blood lactate diagnostic and heart rate (HR) monitoring to determine HR recovery and power output at individual anaerobic threshold (IAT).Results: At baseline, acute exercise miR-222 and -29c levels were increased only in the 4 × 30 HIIT group (both p < 0.01, pre- vs. post-exercise). After the intervention, acute exercise miR-222 levels were still increased in the 4 × 30 HIIT group (p < 0.01, pre- vs. post-exercise) while in the 8 × 15 HIIT group again no acute effect was observed. However, both HIIT interventions resulted in elevated resting miR-222 and -29c levels (all p < 0.001, pre- vs. post-intervention). Neither of the two miRNAs were elevated at any ICRT speed level at baseline nor follow-up. While HR recovery was improved by >24% in both HIIT groups (both p ≤ 0.0002) speed at IAT was improved by 3.6% only in the 4 × 30 HIIT group (p < 0.0132). Correlation analysis suggested an association between both miRNAs and TGF-beta1 mRNA (all p ≤ 0.006, r ≥ 0.74) as well as change in speed at IAT and change in miR-222 levels (p = 0.024, r = 0.46).Conclusions: HIIT can induce increased circulating levels of cardiac growth-associated miR-222 and -29c. miR-222 and miR-29c could be useful markers to monitor HIIT response in general and to identify optimal work/rest combinations

Dose-Response of High-Intensity Training (HIT) on Atheroprotective miRNA-126 Levels

Aim: MicroRNA-126 (miR-126) exerts beneficial effects on vascular integrity, angiogenesis, and atherosclerotic plaque stability. The purpose of this investigation was to analyze the dose-response relationship of high-intensity interval training (HIIT) on miR-126-3p and -5p levels.Methods: Sixty-one moderately trained individuals (females = 31 [50.8%]; 22.0 ± 1.84 years) were consecutively recruited and allocated into three matched groups using exercise capacity. During a 4-week intervention a HIIT group performed three exercise sessions/week of 4 × 30 s at maximum speed (all-out), a progressive HIIT (proHIIT) group performed three exercise sessions/week of 4 × 30 s at maximum speed (all-out) with one extra session every week (up to 7 × 30 s) and a low-intensity training (LIT) control group performed three exercise sessions/week for 25 min <75% of maximum heart rate. Exercise miR-126-3p/-5p plasma levels were determined using capillary blood from earlobes.Results: No exercise-induced increase in miR-126 levels was detected at baseline, neither in the LIT (after 25 min low-intensity running) nor the HIIT groups (after 4 min of high-intensity running). After the intervention, the LIT group presented an increase in miR-126-3p, while in the HIIT group, miR-126-3p levels were still reduced (all p < 0.05). An increase for both, miR-126-3p and -5p levels (all p < 0.05, pre- vs. during and post-exercise) was detected in the proHIIT group. Between group analysis revealed that miR-126-3p levels after LIT and proHIIT increased by 2.12 ± 2.55 and 1.24 ± 2.46 units (all p < 0.01), respectively, compared to HIIT (−1.05 ± 2.6 units).Conclusions: LIT and proHIIT may be performed to increase individual miR-126 levels. HIIT without progression was less effective in increasing miR-126

Creatine loading and resting skeletal muscle phosphocreatine flux: a saturation-transfer NMR study.

31P saturation-transfer nuclear magnetic resonance spectroscopy was used to study skeletal muscle phosphocreatine (PCr) flux in healthy male volunteers. Data analysis included consideration of effects from incomplete saturation and radiofrequency spillover. Spectra were recorded from the resting gastrocnemius muscle before and after 6 days of creatine monohydrate (Cr-H2O) intake (20 g/day). Parallel to an improved muscle performance during maximal intermittent exercise following Cr-H2O supplementation, the concentration of PCr increased (P=0.01) by 23% (34.9+/-2.8 mmol/l vs. 28.6+/-2.7 mmol/l), whereas other metabolites were unaffected (inorganic phosphate: 4.3+/-1.4 mmol/l, free intracellular Mg(2+): 1.1+/-0.7 mmol/l, cytosolic pH: 7.04+/-0.02). Forward and reverse fluxes through the creatine kinase (CK) reaction did not change significantly from their baseline levels (v(for): 11.8+/-5.4 mmol/l per second vs. 15.3+/-6.8 mmol/l per second, (v(rev): 9.5+/-3.4 mmol/l per second vs. 10.9+/-3.7 mmol/l per second). The rate of PCr resynthesis in resting muscle is not limited by the CK reaction, which is near equilibrium. Consequently, the post-load increase in total creatine has no effect on the unidirectional CK reaction rates