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.

Effects of a 25-km trial on psychological, physiological and stroke characteristics of short- and mid-distance swimmers.

AIM: The aim of this paper was to evaluate the effects of a very long distance swimming task on psychological, biomechanical and physiological responses. Eight swimmers (age 21.0 ± 1.2 years; stature 1.80 ± 0.07 m; body mass 76.7 ± 11.0 kg; means ± SD) participated in a 25-km trial in a swimming pool. METHODS: Before and immediately after the trial, swimmers underwent a 50-m sprint test, during which we assessed velocity, stroke rate (SR), stroke length (SL) and psychological condition (rate of perceived exertion [RPE] and profile of mood state [POMS] questionnaire). During the 25-km trial we determined also elbow angle, heart rate (HR) and lactate concentration ([La]). RESULTS: Velocity, SR and SL during the sprint test after the trial decreased compared to before from 1.91 ± 0.01 m·s⁻¹, 0.94 ± 0.01 cycles·s⁻¹ and 1.99 ± 0.02 m·cycle⁻¹ to 1.45 ± 0.01 m·s⁻¹, 0.78 ± 0.01 cycles·s⁻¹ and 1.84 ± 0.03 m·cycle⁻¹, respectively (P<0.05). During the 25-km trial, velocity and SL decreased significantly, while SR and elbow angle did not change. Velocity and SR during the sprint test after the trial were significantly higher than those during the trial. RPE and fatigue (POMS subscale) increased significantly, while the other negative POMS subscales and vigor decreased significantly. HR decreased significantly at 20 km, then increasing significantly at 25 km, while [La] did not change. CONCLUSION: These results suggest that, despite the occurrence of fatigue, as evidenced by the drop in velocity and changes in psychological profile, swimmers were able to complete the 25-km trial by adopting a conservative pacing, unveiling also a reserve in maximum performance.

Ultrasound and laser as stand-alone therapies for myofascial trigger points: a randomized, double-blind, placebo-controlled study.

BACKGROUND AND PURPOSE: Ultrasound (US) and low-level laser therapy (LLLT) are commonly employed for myofascial trigger points (MTP) despite lack of evidence for usage as stand-alone treatments. The aim of the study was to determine, on MTP of the upper trapezius muscle (uTM), the effects of US and LLLT per se, as delivered in accordance with the procedures reported by surveys about their usage among physiotherapists. METHODS: Design was set as a double-blind, randomized, placebo-controlled study. Sixty participants with at least one active MTP in uTM (28 women and 32 men; mean age 24.5 ± 1.44 years) were recruited and randomly assigned to one out of five groups: active US (n = 12), placebo US (n = 12), active LLLT (n = 11), placebo LLLT (n = 11) and no therapy (control, n = 14). The participants and outcome assessor were blinded to the group assignment and therapy delivered. Three outcome measures were assessed at baseline, after a 2-week treatment and 12 weeks after the end of the intervention (follow-up): pressure pain threshold, subjective pain on a numerical rating scale and muscle extensibility performing a cervical lateral flexion. All subjects assigned to the intervention groups were treated five times weekly for overall 10 treatments given. Two-way ANOVA was used to compare differences before and after intervention and among groups at each time-point. RESULTS: After the 2-week intervention, all groups showed pressure pain threshold, numerical rating scale and cervical lateral flexion significant improvements (p < 0.05), which were confirmed at the follow-up. When performing multiple comparisons, controls scored significantly less than both the active therapies and placebos, whereas no differences were detected between active therapies and placebos. CONCLUSIONS: Ultrasound and LLLT provided significant improvements in pain and muscle extensibility, which were superior to no therapy but not to placebos, thus raising concerns about the suitability, both economically and ethically, of administering such common physical modalities as stand-alone treatments in active MTP of the uTM.

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.

Cycling efficiency and time to exhaustion are reduced after acute passive stretching administration.

The aim of this study was to assess the effects of acute passive stretching on cycling efficiency during an exercise of heavy intensity. After maximum aerobic power (VO(2max)) assessment, nine active males (24 ± 5 years; stature 1.71 ± 0.09 m; body mass 69 ± 7 kg; mean ± standard deviation) performed tests at 85% of VO(2max) (W(85)) until exhaustion, with and without pre-exercise stretching. During the tests, we determined the gas exchange, metabolic and cardiorespiratory parameters. With stretching, no differences in VO(2max) occurred (3.64 ± 0.14 vs 3.66 ± 0.07 L/min for stretching and control, respectively). During W(85), pre-exercise stretching (i) decreased time to exhaustion (t(lim)) by 26% (P<0.05); (ii) increased average VO(2) by 4% (3.24 ± 0.07 and 3.12 ± 0.07 L/min in stretching and control, respectively; P<0.05); and (iii) reduced net mechanical efficiency (e(net) ) by 4% (0.185 ± 0.006 and 0.193 ± 0.006 in stretching and control, respectively; P<0.05). Although acute passive stretching did not have an effect on VO(2max), t(lim) and e(net) during heavy constant load exercise were significantly affected. These results are suggestive of an impairment in cycling efficiency due to changes in muscle neural activation and viscoelastic characteristics induced by stretching.

Acidosis láctica y diabefén / Lactic acidosis and diabephen

Un estudio para conocer la aparición de acidosis láctica con el uso del diabefén, fue realizado con 32 pacientes diabéticos ingresados en el Instituto de Angiología, los cuales recibieron una dosis total diaria de 100 mg de diabefén o fenformín, para controlar su diabetes, normalizar la fibrinólisis o ambas. Se evaluó semanalmente (1-6 semanas) la concentración de lactato en sangre venosa, así como niveles sanguíneos de urea y creatinina para correlacionar posible afectación renal. Se concluye que a la dosis y tiempo empleados, no se presentó en nuestra serie ningún caso de acidosis láctica, pero que tampoco existió aparente daño renal(AU)

Amputaciones "económicas". Valor de la cirugía hiperemiante y revascularizadora en los pacientes con arteriopatía diabética / "Economic" amputations. Value of hyperemizating and revascularizing surgery in patients with diabetic arteropathy

Se realiza un estudio en 122 pacientes con pie diabético isquémico con el objetivo de medir la influencia de las cirugías hiperemiantes y revascularización o ambas, tanto sobre el índice de amputaciones mayores como sobre la tasa de mortalidad y el promedio de estadía. Dicho índice fue de 76 por ciento en los 79 pacientes a quienes no se les había realizado simpatectomía, revascularización o ambas antes de la amputación y de sólo 55,8 por ciento en los 43 pacientes restantes que se les había hecho tales operaciones. Esta diferencia resultó altamente significativa desde el punto de vista estadístico. La realización de las cirugías hiperemiantes, revascularizadora o ambas, no influyó en la tasa de mortalidad y sí en el promedio de estadía, que fue 13 días más elevado en los pacientes que la recibieron. Se hacen algunas consideraciones en cuanto a la importancia de un diagnóstico precoz de la angiopatia diabética, que posibilite la utilización oportuna de estos procedeceres como ayuda eficaz en la reducción de la tasa de incidencia de amputaciones mayores en la población diabética y en el logro de amputaciones "económicas"(AU)