Specific adaptations in performance and muscle architecture after weighted jump-squat vs body mass squat jump training in recreational soccer players

The aim of the present study was to compare the effects of weighted jump squat (WJST) vs body mass squat jump training (BMSJT) on quadriceps muscle architecture, lower-limb lean-mass (LM) and muscle strength, performance in change of direction (COD), sprint and jump in recreational soccer-players. Forty-eight healthy soccer-players participated in an off-season randomized controlled-trial. Before and after an eight-week training intervention, vastus lateralis pennation angle, fascicle length, muscle thickness, LM, squat 1-RM, quadriceps and hamstrings isokinetic peak-torque, agility T-test, 10 and 30m sprint and squat-jump (SJ) were measured. Although similar increases in muscle thickness, fascicle length increased more in WJST (ES=1.18, 0.82-1.54) than in BMSJT (ES=0.54, 0.40-0.68) and pennation angle only increased in BMSJT (ES=1.03, 0.78-1.29). Greater increases in LM were observed in WJST (ES=0.44, 0.29-0.59) than in BMSJT (ES=0.21, 0.07-0.37). Agility T-test (ES=2.95, 2.72-3.18), 10m (ES=0.52, 0.22-0.82) and 30m-sprint (ES=0.52, 0.23-0.81) improved only in WJST, while SJ improved in BMSJT (ES=0.89, 0.43-1.35) more than in WJST (ES=0.30, 0.03-0.58). Similar increases in squat 1-RM and peak-torque occurred in both groups. The greater inertia accumulated within the landing-phase in WJST vs BMSJT has increased the eccentric workload, leading to specific eccentric-like adaptations in muscle architecture. The selective improvements in COD in WJST may be related to the increased braking ability generated by the enhanced eccentric workload

Local and systemic vascular hemodynamic response to passive static stretching in young healthy humans

The aim of the present study was to determine the acute effects of passive static stretching (PSS) on femoral blood flow (FBF) in a stretched and non-stretched limb. Our hypothesis was that PSS would increase FBF in the stretched limb mainly through local vasodilator mechanisms. PSS effects may be expected also in the non-stretched limb possibly through an imbalance between the systemic hemodynamic control and the local vasodilator response. To this purpose, eight young healthy individuals (age: 22\ub13 yrs) underwent PSS (5 cycles of 45 s stretch/15 s rest) of the knee extensors of the dominant limb. Femoral artery blood velocity and diameter were taken from both limbs by ultrasound. FBF was then calculated. PSS increased FBF by 3c78% in the stretched limb (from 495\ub1110 to 882\ub1121 ml/min; P<0.05). FBF returned to baseline within the end of the 45 s stretch. Conversely, FBF decreased transitory by 3c71% (from 334\ub1155 to 138\ub117 ml/min; P<0.05) in the non-stretched limb during PSS maneuver. In conclusion, PSS increased FBF in the stretched limb, and induced a FBF decrease in the contralateral limb. These findings may suggest the predominance of a local vasodilator mechanism in the stretched limb during PSS maneuver, probably induced by nitric oxide release. On the contrary, a possible systemic vasoconstriction, likely mediated by an elevation of sympathetic nerve activity, may prevail in the contralateral limb

Evidence of Improved Vascular Function in the Arteries of Trained but Not Untrained Limbs After Isolated Knee-Extension Training

Vascular endothelial function is a strong marker of cardiovascular health and it refers to the ability of the body to maintain the homeostasis of vascular tone. The endothelial cells react to mechanical and chemical stimuli modulating the smooth muscle cells relaxation. The extent of the induced vasodilation depends on the magnitude of the stimulus. During exercise, the peripheral circulation is mostly controlled by the endothelial cells response that increases the peripheral blood flow in body districts involved but also not involved with exercise. However, whether vascular adaptations occur also in the brachial artery as a result of isolated leg extension muscles (KE) training is still an open question. Repetitive changes in blood flow occurring during exercise may act as vascular training for vessels supplying the active muscle bed as well as for the vessels of body districts not directly involved with exercise. This study sought to evaluate whether small muscle mass (KE) training would induce improvements in endothelial function not only in the vasculature of the lower limb (measured at the femoral artery level in the limb directly involved with training), but also in the upper limb (measured at the brachial artery level in the limb not directly involved with training) as an effect of repetitive increments in the peripheral blood flow during training sessions. Ten young healthy participants (five females, and five males; age: 23 \ub1 3 years; stature: 1.70 \ub1 0.11 m; body mass: 66 \ub1 11 kg; BMI: 23 \ub1 1 kg \ub7 m 122 ) underwent an 8-week KE training study. Maximum work rate (MWR), vascular function and peripheral blood flow were assessed pre- and post-KE training by KE ergometer, flow mediated dilatation (FMD) in the brachial artery (non-trained limb), and by passive limb movement (PLM) in femoral artery (trained limb), respectively. After 8 weeks of KE training, MWR and PLM increased by 44% (p = 0.015) and 153% (p = 0.003), respectively. Despite acute increase in brachial artery blood flow during exercise occurred (+25%; p &lt; 0.001), endothelial function did not change after training. Eight weeks of KE training improved endothelial cells response only in the lower limb (measured at the femoral artery level) directly involved with training, likely without affecting the endothelial response of the upper limb (measured at the brachial artery level) not involved with training

Respiratory muscle training affects peripheral vascular function

Introduction Changes in breathing patterns, that are influenced by respiratory muscle training (RMT)(1), may also affect the autonomic balance by decreasing sympathetic drive and improve vascular function (2). Therefore, the aim of this study was to evaluate the efficacy of RMT on vascular function, assessed by flow mediated dilation (FMD), in young healthy subjects. Our hypothesis was that RMT could ameliorate both lung functions and brachial-artery FMD without affecting sympathetic and parasympathetic neural drive. Methods Twenty-three physically active participants were randomly assigned to an RMT group (TG: age 27\ub18 yrs, BMI 24\ub14 kg\ub7m-2; RMT 3 times a week for 2 months, 15-30 minutes of progressive RMT assessed weekly) or to a sham group (SG: age 33\ub111 yrs, BMI 24\ub14 kg\ub7m-2; 3 times a week for 2 months of RMT-Placebo). Maximal inspiratory mouth pressure (MIP) and maximum voluntary ventilation (MVV) were utilized to assess the pulmonary effects of RMT. Heart rate variability (HRV, the ratio between low and high frequency: LF/HF) was utilized to assess the autonomic balance. Vascular function was determined by measuring vessel vasodilation (%FMD), normalized by the shear rate (FMD/SR). Results After 2 months of RMT, MIP and MVV increased significantly by 25% and 8%, respectively, while in the SG, MIP and MVV didn\u2019t change. In both TG and SG the changes in LF/HF were negligible. However, vascular function improved significantly only in TG (FMD/SR TG = -31 % FMD/SR; SG = -4 % FMD/SR). Discussion Data from the current study indicate a positive effect of RMT on both pulmonary and vascular function. However, contrary to our hypothesis, these positive results seem not primarily induced by adaptations of the autonomic balance. Therefore, physiological factors other than the modulation of sympathetic and parasympathetic nerve activity, seem positively triggered by the RMT (3). Reference

Effects of respiratory muscles training on vascular function

Aim: Respiratory muscles training (RMT) leads to a decrease in sympathetic drive and to a subsequent drop in systolic and diastolic blood pressure. This may improve vascular function. However, scientific evidence is actually lacking about the effects of RMT on vascular function. Methods: Eighteen physically active participants (5 males and 13 females) were randomly assigned to a training group (TG: age 27\ub18, BMI 24\ub14; RMT 3 times a week for 2 months) or to a sham group (SG: age 34\ub115, BMI 24\ub14; 8 weeks of RMT familiarization) after 1 week of familiarization. Maximal inspiratory mouth pressure (MIP) and maximum voluntary ventilation (MVV) were utilized to assess the effects of RMT. Heart rate variability (HRV) defined the activity of autonomic nervous system. Vascular function was assessed by pulse wave velocity (PWV), flow mediated dilation (FMD) and carotid lumen diameter (cLD) through ultrasound measurements. Results: After 8 weeks, MIP and MVV increased by ~40% and ~9%, respectively, in TG (P<0.05), but not in SG. However, no differences were found in HRV parameters and in PWV, FMD, cLD values after RMT. Conclusion: Despite a significant effect on MIP and MVV, data from the current study indicate a not detectable effect of RMT on vascular function. Therefore, the increase in respiratory function didn\u2019t induce changes in vascular function, likely because of the normal sympathetic drive and normal blood pressure of the selected participants. Further studies on hypertensive individuals may be required to disclose RMT effects on vascular function

Effects of Isolated Muscle Training on Vasomotor Response and Peripheral Blood Flow

The vasomotor response, a marker of cardiovascular health, refers to the adaptability of the inner lining of blood vessels to maintain the homeostasis of vascular tone. The two main control systems that underpin this response are: the systemic autonomic control, with the sympathetic branch mediated vasoconstriction, and the endothelial cells response to mechanical and chemical stimuli, that results in smooth muscles cell vasodilation. During exercise the peripheral circulation is mostly mediated by local control, and the peripheral blood flow (BF) increases in all body districts directly involved and not involved by physical exercise. The vasodilation response depends on the magnitude of the stimulus received. To date, vascular adaptations in the brachial artery not involved in an isolated leg muscle training, is still unclear/unknown. Repetitive changes in BF occurring during exercise training may act as vascular training for vessels supplying the active muscle bed and ones distal to the active muscle. Therefore, the study aim was to evaluate the effects of isolated quadriceps muscle training (IQT) on vasomotor response in the lower limb directly involved with exercise (femoral artery) and on the upper limb, not involved with IQT (brachial artery). Ten healthy participants (4 M and 6 F; 23\uf0b13 yrs) underwent eight weeks of IQT (3days/week; \u334 40min; 50 - 90% WRM) at different intensities. Maximum work rate (MWR) was assessed before, during (every 2 weeks, to redefine the training work-load) and after IQT. Pre- and post-IQT measurements of vascular function and peripheral BF were performed by flow mediated dilatation (%FMD) in the brachial artery (non-trained limb), and by passive limb movement in femoral artery (trained limb). After 8 weeks of IQT, MWR and BF in femoral artery increased significantly by 43% and 153%, respectively. No difference in %FMD was found despite 21% increase in brachial artery blood flow during exercise was found. Eight weeks of IQT improved peripheral vasomotor response only in the lower limb directly involved in IQT without affecting vascular functionality in the uninvolved upper limb, suggesting that IQT did not provide a sufficient stimulus to induce adaptations also in other districts\u2019 vasculature

Central and peripheral responses to static and dynamic stretch of skeletal muscle: mechano- and metabo-reflex implications

Passive static stretching (SS), circulatory cuff occlusion (CCO), and the combination of both (SS+CCO) have been used to investigate the mechano- and metabo-reflex, respectively. However, the effects of dynamic stretching (DS) alone or in combination with CCO (DS+CCO) on the same reflexes have never been explored. The aim of the study was to compare central and peripheral hemodynamic responses to DS, SS, DS+CCO, and SS+CCO. In ten participants, femoral blood flow (FBF), heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were assessed during DS and SS of the quadriceps muscle with and without CCO. Blood lactate concentration [La-] in the lower limb undergone CCO was also measured. FBF increased significantly in DS and SS by 365\ub198 and 377\ub1102 ml/min, respectively. Compared to baseline, hyperemia was negligible during DS+CCO and SS+CCO (+11\ub198 and +5\ub187 ml/min, respectively). DS generated a significant, sustained increase in HR and CO (40s), while SS induced a blunted and delayed, cardioacceleration (20s). After CCO, [La-] in the lower limb increased by 135%. Changes in HR and CO during DS+CCO and SS+CCO were similar to DS and SS alone. MAP decreased significantly by 5% during DS and SS, didn't change in DS+CCO, and increased by 4% in SS+CCO. The present data indicate a reduced mechano-reflex response to SS compared to DS (i.e., different HR and CO changes). SS evoked a hyperemia similar to DS. The similar central hemodynamics recorded during stretching and [La-] accumulation suggest a marginal interaction between mechano- and metabo-reflex

Static stretching negatively affect exercise endurance via reducing functional sympatholysis

Aim: Exercise results in an increase in metabolism and the favorable redistribution of blood flow to the active area, by locally attenuating the vasoconstriction caused by the global increase in muscle sympathetic nerve activity, a process known as \u201cfunctional sympatholysis\u201d. The recent recognition that passive leg stretching (PLS) negatively affect exercise endurance by reducing mechanical efficiency and increasing accumulation metabolism byproducts, instigates the question does PLS affect functional sympatholysis? Methods: Therefore, in 8 healthy subjects (25\ub13 yr) femoral artery blood flow (FBF) was measured during a time to exhaustion (85% of maximal work rate) of a dynamic knee extension (KE) exercise. The measurement was repeated during the same exercise executed immediately after 5 min of passive leg stretching (KE+PLS). Results: Time to limit during the KE+PLS was decreased by 26%. Similarly FBF during KE+PLS was also reduced by the 26%. Conclusions: These data reveal that 5 minutes of passive leg stretching does result in a extensive reduction ~26% in femoral blood flow. Interestingly, the time to limit was decreased by the same extend, implicating a possible association between the reduction of functional sympatholysis and the decrease of endurance performance. This PLS-induced reduction in oxygen delivery to the exercising skeletal muscle was likely determined by mechanical, neuromuscular, and biochemical factors, but other studies are needed to extend these preliminary results

Exercise pressor reflex during static and dynamic skeletal muscle stretching

Aim: Passive static stretching (SS), arterial occlusion (C), and the combination of both procedures (SS+C) has been used to stimulate group III and IV afferents of the exercise pressor reflex. However, the effects of dynamic passive stretching (DS) and arterial occlusion (DS+C) on the exercise pressor reflex are not fully elucidated. Therefore, the aim of the present study was to compare central and peripheral response to DS, SS, DS+C, and SS+C. Methods: In twelve healthy volunteers, femoral blood flow (FBF), heart rate (HR), cardiac output (CO), and mean arterial pressure (MAP) were assessed during DS and SS of the quadriceps muscle. The same procedures were repeated with arterial occlusion of lower limb (upper-thigh cuff inflated at 250 mmHg). Results: FBF increased significantly in both DS and SS by 365\ub198 and 377\ub1102 ml/min. This hyperaemia was ablated during DS+C and SS+C by 11\ub198 and 5\ub187ml/min. The increase in HR was similar (~4.2 bpm for DS, SS, DS+C, and SS+C). Likewise, the change in CO was ~0.30 l/min. MAP dropped by -4.7\ub11.2 and -4\ub11.4 mmHg during DS and SS, while it increased by 3.7\ub11.6, and 4.8\ub11.3 mmHg for DS+C and SS+C. Conclusions: Data from the current study indicated a similar group III afferents response to DS, SS (i.e., equal HR and CO changes). HR and CO findings during DS+C and SS+C suggested no evidence of interaction between group III and IV afferents. Conversely, the MAP reduced only during DS and SS, because of a limb induced-hyperaemia