Evidence for improved systemic and local vascular function after long-term passive static stretching training of the musculoskeletal system.

KEY POINTS: Vascular function and arterial stiffness are important markers of cardiovascular health and cardiovascular co-morbidity. Transitional phases of hypoemia and hypermia, with consequent fluctuations in shear rate, occuring during repetitive passive stretching adminstration (passive stretching training) may constitute an effective stimulus to induce an amelioration in vascular function, arterial stiffness and vascular remodelling by improving central and local blood flow control mechanisms. Vascular function, arterial stiffness and vascular remodelling were evaluated before and after 12 weeks of passive stretching training and after 6 weeks from training cessation, in the femoral, popliteal (treated with stretching), and brachial arteries (untreated) of both sides. After passive stretching training, vascular function and arterial remodelling improved, and arterial stiffness decreased in all the arteries, suggesting modifications of both central and local blood flow control mechanisms. Passive stretching-induced improvements related to central mechanisms seemed to have a short duration, as they returned to pre-training baseline within 6 weeks from training cessation, whereas those more related to a local mechanism persisted in the follow-up. ABSTRACT: Acute passive stretching (PS) effects on blood flow ( Q̇ ), shear rate ( Ẏ ), and vascular function in the feeding arteries of the stretched muscle have been extensively investigated; however, few data are available on vascular adjustments induced by long-term PS training. We investigated the effects of PS training on vascular function and stiffness of the involved (femoral and popliteal) and uninvolved (brachial) arteries. Our hypothesis was that PS-induced changes in Q̇ and Ẏ would improve central and local mechanisms of Q̇ control. Thirty-nine participants were randomly assigned to bilateral PS (n = 14), monolateral PS (n = 13) or no PS training (n = 12). Vascular function was measured before and after 12 weeks of knee extensor and plantar flexor muscles' PS training by single passive limb movement and flow-mediated dilatation (FMD). Central (carotid-femoral artery PWV, PWVCF ) and peripheral (carotid-radial artery PWV, PWVCR ) arterial stiffness was measured by pulse-wave velocity (PWV), together with systolic (SBP) and diastolic (DBP) blood pressure. After PS training, increases of 30%, 25% and 8% (P < 0.05) in femoral Δ Q̇ , popliteal and brachial artery FMD%, respectively, occurred in both PS training groups. A decrease in PWVCF , PWVCR , SBP and DBP (-25%, -17%, -4% and -8%, respectively; P < 0.05) was noted. No changes occurred in controls. Vascular function improved and arterial stiffness reduced in the arteries involved and uninvolved with PS training, suggesting modifications in both central and local Q̇ control mechanisms. PS-induced improvements had a short duration in some of vascular function parameters, as they returned to baseline within 6 weeks of PS training cessation.

Changes in energy system contributions to the Wingate anaerobic test in climbers after a high altitude expedition.

PURPOSE: The Wingate anaerobic test measures the maximum anaerobic capacity of the lower limbs. The energy sources of Wingate test are dominated by anaerobic metabolism (~ 80%). Chronic high altitude exposure induces adaptations on skeletal muscle function and metabolism. Therefore, the study aim was to investigate possible changes in the energy system contribution to Wingate test before and after a high-altitude sojourn. METHODS: Seven male climbers performed a Wingate test before and after a 43-day expedition in the Himalaya (23 days above 5.000 m). Mechanical parameters included: peak power (PP), average power (AP), minimum power (MP) and fatigue index (FI). The metabolic equivalents were calculated as aerobic contribution from O2 uptake during the 30-s exercise phase (WVO2), lactic and alactic anaerobic energy sources were determined from net lactate production (WLa) and the fast component of the kinetics of post-exercise oxygen uptake (WPCr), respectively. The total metabolic work (WTOT) was calculated as the sum of the three energy sources. RESULTS: PP and AP decreased from 7.3 ± 1.1 to 6.7 ± 1.1 W/kg and from 5.9 ± 0.7 to 5.4 ± 0.8 W/kg, respectively, while FI was unchanged. WTOT declined from 103.9 ± 28.7 to 83.8 ± 17.8 kJ. Relative aerobic contribution remained unchanged (19.9 ± 4.8% vs 18.3 ± 2.3%), while anaerobic lactic and alactic contributions decreased from 48.3 ± 11.7 to 43.1 ± 8.9% and increased from 31.8 ± 14.5 to 38.6 ± 7.4%, respectively. CONCLUSION: Chronic high altitude exposure induced a reduction in both mechanical and metabolic parameters of Wingate test. The anaerobic alactic relative contribution increased while the anaerobic lactic decreased, leaving unaffected the overall relative anaerobic contribution to Wingate test.

Evidence of balance training-induced improvement in soccer-specific skills in U11 soccer players.

The present study aimed to determine the role of balance training improving technical soccer skills in young players. Two U11 soccer teams were randomly assigned one to either balance training (BT; n = 22) or control group (Ctrl; n = 21). At the end of their habitual soccer training (identical in BT and Ctrl), BT underwent additional balance training for 12 weeks (3 sessions/week, 20 minutes per session), while Ctrl had a 20-minute scrimmage. Before and after the intervention, BT and Ctrl underwent two soccer-specific tests (Loughborough Soccer Passing, LSPT, and Shooting, LSST, Tests), and bipedal and unipedal balance evaluations. After intervention, both groups decreased the trials time and improved passing accuracy, with larger improvements in BT than Ctrl (LSPT penalty time [CI95% ]: -2.20 seconds [-2.72/-1.68]; ES [CI95% ]: -2.54 seconds [-3.34/-1.74]). Both groups improved balance ability, with BT showing larger increments in bipedal tests than Ctrl (static balance: -29 mm [-42/-16]; ES: -1.39 [-2.05/-0.72]; limit of stability: 4% [3/5]; ES 3.93 [2.90/4.95]; unipedal quasi-dynamic balance: 0.07 a.u. [0.03/0.11]; ES: 1.04 [0.40/1.67] and active range of motion: -5% [-8/-2]; ES -0.89 [-1.51/-0.26]). Low-to-moderate correlations between the players' technical level and unipedal balance ability were retrieved, particularly in the non-dominant limb (R from 0.30 to 0.48). Balance training improved some technical soccer skills more than habitual soccer training alone, suggesting that young soccer players may benefit from additional balance training added to their traditional training.

Rest-activity circadian rhythm and sleep quality in patients with binge eating disorder.

Recent findings suggest that altered rest-activity circadian rhythms (RARs) are associated with a compromised health status. RARs abnormalities have been observed also in several pathological conditions, such as cardiovascular, neurological, and cancer diseases. Binge eating disorder (BED) is the most common eating disorder, with a prevalence of 3.5% in women and 2% in men. BED and its associate obesity and motor inactivity could induce RARs disruption and have negative consequences on health-related quality of life. However, the circadian RARs and sleep behavior in patients with BED has been so far assessed only by questionnaires. Therefore, the purpose of this study was to determine RARs and sleep parameters by actigraphy in patients with BED compared to a body mass index-matched control group (Ctrl). Sixteen participants (eight obese women with and eight obese women without BED diagnosis) were recruited to undergo 5-day monitoring period by actigraphy (MotionWatch 8®, CamNtech, Cambridge, UK) to evaluate RARs and sleep parameters. In order to determine the RARs, the actigraphic data were analyzed using the single cosinor method. The rhythmometric parameters of activity levels (MESOR, amplitude and acrophase) were then processed with the population mean cosinor. The Actiwatch Sleep Analysis Software (Cambridge Neurotecnology, Cambridge, UK) evaluated the sleep patterns. In each participant, we considered seven sleep parameters (sleep onset: S-on; sleep offset: S-off; sleep duration: SD; sleep latency: SL; movement and fragmentation index: MFI; immobility time: IT; sleep efficiency: SE) calculated over a period of five nights. The population mean cosinor applied to BED and Ctrl revealed the presence of a significant circadian rhythm in both groups (p < 0.001). The MESOR (170.0 vs 301.6 a.c., in BED and Ctrl, respectively; p < 0.01) and amplitude (157.66 vs 238.19 a.c., in BED and Ctrl, respectively p < 0.05) differed significantly between the two groups. Acrophase was not different between BED and Ctrl, as well as all sleep parameters. Both groups displayed a low level of sleep quality (SE 80.7% and 75.7% in BED and Ctrl, respectively). These data provided the first actigraphy-based evidence of RARs disruption and sleep behavior disorder in patients with BED. However, while sleep disorders could be reasonably ascribed to overweight/obesity and the related lower daily physical activity, RARs disruption in this pathology should be ascribed to factors other than reduced physical activity. The circadian timing approach can represent a novel potential tool in the treatment of patients with eating disorders. These data provide exploratory evidence of behavioral association in a small population of patients that, if confirmed in a wider number of subjects and across different populations, may lead to a revision and enhancement of interventions in BED patients.

Aerobic training program for the enhancements of HR and VO2 off-kinetics in elite judo athletes.

AIM: The purpose of this study was to investigate the physiologic and performance changes with the addition of high-intensity interval training (HIIT) to a traditional judo programme. METHODS: Nine elite judokas (6 males and 3 females; age: 20±4 yrs; body mass: 69±2 kg; height: 172±7 cm; judo practice time: 13±6 yrs; weekly training volume: 13±5 hours, mean±SD) were recruited to perform a 12-week specific aerobic training program, which consisted of 2 session/week of 30-min continuous run at 60% at Vmax and one session/week of high-intensity interval training 15x1-min at 90% of Vmax with 1 min of active recovery at 60% of Vmax. Before and after the intervention all athletes performed a graded maximal exercise Test to measure maximal oxygen consumption (V̇O2max), ventilatory threshold (VT), maximal velocity (Vmax), heart rate (HR) and V̇O2 off kinetics. V̇O2 and HR recovery kinetics were evaluated on a breath-by-breath basis using a single component exponential function. Anaerobic capacity during specific movements was assessed with the Special judo fitness Test (SJFT). RESULTS: The maximal speed reached during the maximal aerobic power test significantly increaseed (P=0.04), but V̇O2max did not change. τ of HR and of V̇O2 recovery significantly decreased by 17.3% (P=0.04) and 22.0% (P<0.01), respectively. VT increased (6.6%; P=0.03) and the SJFT Index improved (12%; P<0.001) 12% after training. CONCLUSION: The aerobic fitness of elite judokas may be improved by adding aerobic routines to the normal training enhancing the recovery capacity.

Relationship between anthropometric or functional characteristics and maximal serve velocity in professional tennis players.

AIM: This study aims at investigating the possible relationships between anthropometric and functional parameters and maximal serve speed in professional tennis players. METHODS: Eight professional male tennis players (age 23±4 [mean±SD] years; height 181±4 cm; body mass 80±4 kg; playing experience 14±4 years; weekly training practice 29±6 hours) were recruited. Anthropometric parameters (height, body mass, arm-racquet length, arm muscle area), jump performance (squat jump, counter movement jump; counter movement jump free), handgrip strength and first and second maximal serve speed were assessed. RESULTS: Pearson's correlation coefficient showed significant (P<0.05) positive relationships between height and ball speed in both the first (r=0.78; P=0.02) and second (r=0.80; P=0.017) serve, and a significant negative correlation between serve speed and arm muscle area in first serve only (r=-0.78; P=0.03). In addition, a trend towards a positive correlation was observed between string tensions and serves speed for both first and second serves (r=0.54; P=0.16 and r=0.60; P=0.11, respectively). No significant relationship was found between serve speed and the other variables considered, including jumping performance parameters. CONCLUSION: Height was confirmed to be the main anthropometric determinant of serves speed in professional tennis players.

Cardiovascular adaptation to mudpack therapy in hypertensive subjects treated with different antihypertensive drugs.

OBJECTIVE: In selected hypertensive subjects, cardiovascular adaptation to warm environments may be inadequate or even harmful: heating associated to mudpack therapy may cause unexpected hypotension. How different antihypertensive drugs may affect the cardiovascular response to mudpack therapy is poorly studied. AIMS: To evaluate the effects of ß-blockers and angiotensin II receptor antagonists/ACE inhibitors on the acute cardiovascular adaptation to mudpack treatment in SPA in elderly hypertensive patients. PATIENTS AND METHODS: Thirty-one elderly subjects were divided in normotensive subjects (N; n=10) and hypertensive patients treated with ACE-inhibitors/Angiotensin II receptor antagonists (HTA; n=12) or with selective ß1-blockers (HTB; n=9). Systolic (SBP) and diastolic (DBP) blood pressure were continuously recorded (10 min) in supine position, immediately before and during mudpack treatment (40°C). Heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were assessed. RESULTS: During mudpack treatment SBP did not significantly change in both HTA and N groups (132±11 and 112±13 mmHg, respectively), but significantly decreased in HTB (111±18 mmHg, p < 0.01 vs baseline) patients. HR increased in all groups (HTA: 72±10 bpm; HTB: 65±6 bpm; N: 70±10 bpm; p < 0.01 vs baseline). A significant reduction (p < 0.01 vs baseline) in SV and CO occurred in HTB, but not in HTA and N groups. TPR significantly increased in HTB (1335±464 dyn.s.cm-5, p < 0.01 vs baseline) but not in HTA and N subjects (1389±385 dyn.s.cm-5 and 1245±323 dyn.s.cm-5, respectively). CONCLUSIONS: Mud treatment did not cause relevant haemodynamic changes in normotensive and HTA-treated hypertensive subjects. Conversely, ß-blocking treatment apparently limited the cardiovascular adaptation to thermic stress, through a possible reduction in myocardial contractility, thereby, causing a significant decrease, although not dangerous, in systolic blood pressure.

Fatigue effects on the electromechanical delay components during the relaxation phase after isometric contraction.

AIM: By a combined electromyographic (EMG), mechanomyographic (MMG) and force (F) analysis, the electromechanical delay during muscle relaxation (R-DelayTOT ) was partitioned into electrochemical and mechanical components. The study aimed to evaluate the effects of fatigue on R-DelayTOT components and to assess their intersession and interday reliability Intraclass correlation coefficient (ICC). METHODS: During tetanic stimulations, EMG, MMG and F were recorded from the human gastrocnemius medialis muscle before and after fatigue. The latency between EMG and MMG ripple cessations (R-Δt EMG-MMGR , electrochemical R-DelayTOT component); between MMG ripple cessation and F decay onset (R-Δt MMGR -F, first R-DelayTOT mechanical component); and between F decay onset and maximum MMG negative peak (R-Δt F-MMGp-p , second R-DelayTOT mechanical component) was calculated. RESULTS: Before fatigue, R-Δt F-MMGp-p was the major contributor (61.9 ± 1.7 ms, 75%) to R-DelayTOT (82.7 ± 1.0 ms), while R-Δt EMG-MMGR and R-Δt MMGR -F accounted for 16% (13.3 ± 1.2 ms) and 9% (7.5 ± 1.0 ms) respectively. After fatigue, R-DelayTOT , R-Δt EMG-MMGR and R-Δt MMGR -F increased by 11, 41 and 67%, respectively (P < 0.05), whereas R-Δt F-MMGp-p did not change. Consequently, the relative contribution of R-Δt EMG-MMGR , R-Δt MMGR -F and R-Δt F-MMGp-p , to R-DelayTOT changed to 20 ± 2, 12 ± 1 and 68 ± 2% respectively. Measurement reliability was always from high to very high (ICC 0.705-0.959). CONCLUSION: Fatigue altered the processes between neuromuscular activation cessation and force decay onset, but not the second mechanical component (cross-bridges detachment rate and series elastic components release). This combined approach provided reliable measurement of the different R-DelayTOT components and it may represent a valid tool to get more insights on muscle electromechanical behaviour.

Effects of tiredness on visuo-spatial attention processes in elite karate athletes and non-athletes.

"Attentional" adaptations are fundamental effects for sport performance. We tested the hypothesis that tiredness and muscular fatigue poorly affect visuo-spatial attentional processes in elite karate athletes. To this aim, 14 elite karate athletes and 11 non-athletes were involved in an isometric contraction exercise protocol up to muscular fatigue. Blood lactate and attention measurements were taken. Posner's test probed "endogenous" (i.e., internally planned allocation of spatial attention) and "reflexive" (i.e., brisk variation of endogenous spatial attention due to unexpected external stimuli) attention. Lactate and attentional measurements were performed before (Block 1, B1) and after the fatiguing exercise (B2) and at the end of a recovery period (B3). Compared to the non-athletes, the athletes showed a better performance in the fatigue protocol, confirmed by the higher absolute lactate values in B2. The correct responses in the "valid trials" probing "endogenous" attention were 92.4% (B1), 93.9% (B2), and 95.8% (B3) in the non-athletes, and 98.5%, 96.4%, 95.5% in the elite karate athletes. The correct responses in the "invalid trials" probing "reflexive" attention were 95.4%, 89.7%, 93.2% in the non-athletes, and 96.4%, 97.3%, 98.5% in the elite karate athletes. The percentage of correct responses in the "invalid" trials significantly decreased from B1 to B2 in the non-athletes but not in the elite karate athletes. In conclusion, tiredness and muscular fatigue do not affect "reflexive" attentional processes of elite karate athletes, which is crucial to contrast attacks coming from an unexpected spatial region.

Maximal instantaneous muscular power after prolonged bed rest in humans.

A reduction in lower limb cross-sectional area (CSA) occurs after bed rest (BR). This should lead to an equivalent reduction in maximal instantaneous muscular power (W(p)) if the body segments' lengths remain unchanged. W(p) was determined during maximal jumps off both feet on a force platform before and on days 2, 6, 10, 32, and 48 after a 42-day duration BR. CSA of thigh muscles was measured by magnetic resonance imaging before and on day 5 after BR. Before BR, W(p) was 3.63 +/- 0.43 kW or 48.6 +/- 3.3 W/kg. On days 2 and 6 after BR, W(p) was reduced by 23.7 +/- 6.9 and 22.7 +/- 5.4% (P < 0.01), respectively. Thigh extensors CSA (CSAEXT) was 16.7 +/- 4.7% (P < 0.01) lower than before. When normalized per CSAEXT, W(p) was reduced by only 4.8 +/- 4.5% (P < 0.05). By day 48 of recovery, W(p) had returned to baseline values. Therefore, if W(p) is appropriately normalized for CSA of the extensor muscles, the reduction in CSAEXT explains most of the decrease in W(p) decrease after BR. Other factors such as a deficit in neural activation or a decrease in fiber-specific tension may account for only 5% of the W(p) loss after BR.