Papers by Lorenzo Bortolan
Journal of Biomechanics, 2022
Although it has already been demonstrated that Nordic walking has some peculiar biomechanical fea... more Although it has already been demonstrated that Nordic walking has some peculiar biomechanical features with respect to walking, the effects on balance and trunk coordination are still unknown. Our aim here was to compare margins of stability, hip stabilizer muscle activation and scapular-pelvis coordination (mean and variability of continuous relative phase) between walking and two different pole walking techniques (observational design). Eleven Nordic walking instructors were asked to walk at 5.5 km·h-1 on a flat treadmill while 1) walking, 2) Nordic walking and 3) pole walking with just elbow flexion-extension motion allowed and constrained shoulder motion (elbow technique). The 3D movements of limbs and poles were measured by an optoelectronic motion capture system, and gluteus medius activation was measured through surface electromyography. Both techniques using poles show larger mediolateral margins of stability and similar anterior-posterior margins of stability in comparison with walking (p < 0.001). The larger mediolateral margin of stability using poles (conditions 2 and 3) is accompanied by greater trunk coordination stability (greater continuous relative phase variability) than walking. Although the Nordic walking (condition 2) technique results in a similar range of scapular and pelvis transverse rotation, the general pattern of scapular-pelvis coordination was temporally delayed by approximately 20% of the gait cycle in relation to other conditions (1 and 3). In conclusion, Nordic walking provides enhanced mediolateral support and coordination stability of trunk compared with walking, suggesting that it could be proposed as a safer exercise modality than walking.
Journal of Thermal Biology, 2021
PURPOSE To investigate the effects of a very short-term acclimation protocol (VSTAP) on performan... more PURPOSE To investigate the effects of a very short-term acclimation protocol (VSTAP) on performance, physiological and perceptual responses to exercise in the heat. METHODS 12 trained male cyclists (age 31.2 ± 7; weight 71.3 ± 7 kg, VO2max: 58.4 ± 3.7 mL/kg/min) randomly performed two Time to Exhaustion Tests (TTE) at 75% of normothermic peak power output (PPO), one in normothermia (N,18°C-50% RH) and one in the heat (H,35°C-50% RH), before and after a VSTAP intervention, consisting of 3 days-90 min exercise (10min at 30% of PPO+80 min at 50% of PPO) in H (≈4.5h of heat exposure). Performance time of TTEs and physiological and perceptual variables of both TTEs and training sessions (T1, T2 and T3) were evaluated. RESULTS Magnitude Based Inferences (MBI) revealed 92/6/1% and 62/27/11% chances of positive/trivial/negative effects of VSTAP of improving performance in H (+17%) and in N (+9%), respectively. Heart Rate (HR) decreased from T1 to T3 (p < 0.001) and T2 to T3 (p < 0.001), whereas Tympanic Temperature (TyT) decreased from T1 to T2 (p = 0.047) and from T1 to T3 (p = 0.007). Furthermore, despite the increased tolerance to target Power Output (PO) throughout training sessions, RPE decreased from T1 to T3 (p = 0.032). CONCLUSIONS The VSTAP determined meaningful physiological (i.e. decreased HR and TyT) and perceptual (i.e. decreased RPE) adaptations to submaximal exercise. Furthermore, showing good chances to improve performance in the heat, it represents a valid acclimation strategy to be implemented when no longer acclimation period is possible. Finally, no cross-over effect of the VSTAP on performance in temperate conditions was detected.
Inclusion of work done by segments could become very informative in comparing XCS techniques char... more Inclusion of work done by segments could become very informative in comparing XCS techniques characterized by completely different pattern of movements. The aims of this study were to assess contribution of Wint to total mechanical work and to compare Wint between diagonal stride (DS), double poling (DP) and double poling with kick (DK
High altitude medicine & biology, 2021
[no abstract available
Metabolic power depends on mean force applied to the ground during a cycle , on rate of force app... more Metabolic power depends on mean force applied to the ground during a cycle , on rate of force application and on cost of force generation. This cost is constant at different speeds and describe the amount of energy spent to perform a Newton of muscular force In a sport where energy consumption, muscular capabilities and force application strategies can influence performance capabilities, the computation of cost of force generation could be a good index of performance ability
The three main techniques in classical cross country skiing, double poling (DP) double poling wit... more The three main techniques in classical cross country skiing, double poling (DP) double poling with kick (DK) and diagonal stride (DS), are characterized by different coordination patterns and by a different involvement of arms and legs. The aim of this study was to compare the cost of locomotion between these techniques on flat and uphill conditions
skiing / Barbara Pellegrini, Lorenzo Bortolan, Hans-Christer Holmberg, Paola Zamparo, Chiara Zopp... more skiing / Barbara Pellegrini, Lorenzo Bortolan, Hans-Christer Holmberg, Paola Zamparo, Chiara Zoppirolli, Federico Schena // Human movement science. – 2013. – № 32 (6). – P. 1415-1429. 4. Contribution of the legs to double-poling performance in elite cross-country skiers / Holmberg H.C., Lindinger S., Stoggl T., Bjorklund G., Muller E. // Med Sci Sports Exerc. – 2006. – Oct. – № 38 (10). – P. 1853-1860. 5. The international ski competition rules (icr). Book II Cross-country [Электронный ресурс] // URL: http://ussa.org/sites/default/files/documents/athletics/nordic/2013-14/documents/icr-cross-country-2013_clean.pdf. – Дата обращения 30.06.2014.
Cross country skiing is characterized by many techniques which differ in contribution offered by ... more Cross country skiing is characterized by many techniques which differ in contribution offered by upper and lower limbs to propulsion. In diagonal stride technique upper and lower body are fully involved in the movement. The aim of this study is to analyze upper body contribution in diagonal stride and the effect of training on specific power expression in elite cross country skiers
High Altitude Medicine & Biology, 2020
Shortening work-rest durations reduces physiological and perceptual load during uphill walking in... more Shortening work-rest durations reduces physiological and perceptual load during uphill walking in simulated cold high-altitude conditions. High Alt Med Biol. 21:249-257, 2020. Background: We investigated the effects of two different work-rest durations on the physiological and perceptual responses to a simulated mountain hike in a cold hypoxic environment. Materials and Methods: Twelve healthy nonacclimatized active men (age 31.3-5.3 years, body mass index 22.4-1.5 kg/m 2) completed a 80-minute work-matched intermittent exercise on a motorized treadmill (25% incline, fixed self-selected speed), in a simulated mountain environment (-25°C, FiO 2 = 11%, &5000 m a.s.l.), wearing extreme cold weather gear, once with short (20 • 3 minutes walking with 1 minute rest; SHORT) and once with long (10 • 6 minutes walking with 2 minutes rest; LONG) work-rest durations. Heart rate (HR), pulse oxygen saturation (SpO 2), rate of perceived exertion (RPE), and thermal sensation (TS) were assessed throughout the exercise protocols. Cardiac autonomic modulation was assessed before (PRE) and after exercise (POST) in supine position, as well as during standing resting periods by means of HR recovery (HRR) assessment. Results: SpO 2 and TS were similar (p > 0.05) in SHORT and LONG protocols. HR and RPE were increased, and HRR reduced during LONG compared to SHORT (p < 0.05). Parasympathetic activity indices were reduced at POST after both protocols (p < 0.05), but to a lesser extent after SHORT (p < 0.05). Conclusions: Reduced work-rest durations are associated with improved perceptual responses and less perturbation of cardiac autonomic balance, compared to longer work-rest durations. Shorter exercise periods from more frequent breaks during hikes at high altitude may represent a valid strategy to limit the impact of exercise under extreme environmental conditions.
Scandinavian Journal of Medicine & Science in Sports, 2017
Nordic walking is a form of walking that includes a poling action, and therefore an additional su... more Nordic walking is a form of walking that includes a poling action, and therefore an additional subtask, with respect to conventional walking. The aim of this study was to assess whether Nordic walking required a task-specific muscle coordination with respect to conventional walking. We compared the electromyographic (EMG) activity of 15 upper and lower limb muscles of nine Nordic walking instructors, while executing Nordic walking and conventional walking at 1.3 ms-1 on a treadmill. Non-negative matrix factorization method was applied to identify muscle synergies, representing the spatial and temporal organization of muscle coordination. The number of muscle synergies was not different between Nordic Accepted Article This article is protected by copyright. All rights reserved. walking (5.2±0.4) and conventional walking (5.0±0.7, p=0.423). Five muscle synergies accounted for 91.2±1.1% and 92.9±1.2% of total EMG variance in Nordic walking and conventional walking, respectively. Similarity and cross-reconstruction analyses showed that four muscle synergies, mainly involving lower limb and trunk muscles, are shared between Nordic walking and conventional walking. One synergy acting during upper limb propulsion is specific to Nordic walking, modifying the spatial organization and the magnitude of activation of upper limb muscles compared to conventional walking. The inclusion of the poling action when Nordic walking do not require an increased complexity of movement control, making Nordic walking suitable for adapted physical activity programs that involve also subjects with low motor skill.
Journal of Sport and Health Science, 2020
analysis of the "running" vs. "conventional" diagonal stride uphill techniques as performed by el... more analysis of the "running" vs. "conventional" diagonal stride uphill techniques as performed by elite crosscountry skiers,
Sport Sciences for Health, 2017
When GE was included in the analysis, the regression model was significantly improved (adjusted R... more When GE was included in the analysis, the regression model was significantly improved (adjusted R 2 = 0.90, p = 0.031). Conclusions The study showed that the mean power output sustained during a vertical race is close to the power associated with VT2 and it is highly correlated with athletes' physiological characteristics. Particularly, two variables, VO 2 at VT2 and GE, measurable with a specific GXT, accounted for the 90% of performance variation in a ski-mountaineering vertical race. Accordingly, training programs should focus on the maximal development of VT2 as well as on increasing GE by technical improvement.
European journal of applied physiology, Jan 26, 2018
This study investigated the effects of acute hypoxic exposure on post-exercise cardiac autonomic ... more This study investigated the effects of acute hypoxic exposure on post-exercise cardiac autonomic modulation following maximal cardiopulmonary exercise testing (CPET). Thirteen healthy men performed CPET and recovery in normoxia (N) and normobaric hypoxia (H) (FiO = 13.4%, ≈ 3500 m). Post-exercise cardiac autonomic modulation was assessed during recovery (300 s) through the analysis of fast-phase and slow-phase heart rate recovery (HRR) and heart rate variability (HRV) indices. Both short-term, T30 (mean difference (MD) 60.0 s, 95% CI 18.2-101.8, p = 0.009, ES 1.01), and long-term, HRRt (MD 21.7 s, 95% CI 4.1-39.3, p = 0.020, ES 0.64), time constants of HRR were higher in H. Fast-phase (30 and 60 s) and slow-phase (300 s) HRR indices were reduced in H either when expressed in bpm or in percentage of HR (p < 0.05). Chronotropic reserve recovery was lower in H than in N at 30 s (MD - 3.77%, 95% CI - 7.06 to - 0.49, p = 0.028, ES - 0.80) and at 60 s (MD - 7.23%, 95% CI - 11.45 to - 3...
Scandinavian Journal of Medicine & Science in Sports, 2016
European Journal of Applied Physiology, 2017
Conclusions A progressively earlier activation of trunk and lower limb muscles is a coordinative ... more Conclusions A progressively earlier activation of trunk and lower limb muscles is a coordinative strategy that allows rapid achievement of optimal body posture prior to the exertion of poling phase. Moreover, earlier activation of these muscles as the speed increases provides adequate muscle stiffness in the shoulder and core regions for the acceptance of the poling load.
Sport Sciences for Health, 2016
Background Whole-body electromyostimulation (WB-EMS) has become increasingly popular under the pr... more Background Whole-body electromyostimulation (WB-EMS) has become increasingly popular under the promise to offer a time-saving and effective exercise protocols. Few studies estimating the training intervention intensity of WB-EMS are available in the literature. Aim The aim of this study was first to estimate the metabolic demand and muscle fatigue induced by a training session with WB-EMS, and second to compare them to a control intervention. Methods Ten young participants performed two training sessions: an experimental condition constituted by five exercises with superimposed WB-EMS and a control condition constituted by five body weight exercises. Both sessions lasted 15 min and were based on isometric intermittent contraction (6 of contraction interspersed by 4 s of rest). Muscle fatigue was assessed by determining the force decrease in the following tests: isometric mid-thigh pull; plyometric push-up; counter-movement jump. Oxygen consumption and energy expenditure were recorded by measuring respiratory gases exchange to quantify the metabolic demand of the exercises. Results The WB-EMS intervention required greater volume of oxygen consumed (WB-EMS 1584 ± 251 ml/min; control 1465 ± 216 ml/min, p = 0.006) and energy expenditure (WB-EMS 470 ± 71 kcal/h; control 438 ± 61 kcal/h, p = 0.013) than in control intervention. Overall, the WB-EMS training induced muscle fatigue (all PRE vs POST tests p B 0.02) whereas the body weight exercises did not (all p [ 0.14). Conclusions These results indicate that WB-EMS intervention constituted a vigorous physical activity. The WB-EMS required also a greater metabolic demand and greater muscle fatigue than a traditional body weight circuit training. Thus, WB-EMS can be considered as an alternative training tool for physically active individuals. Keywords Muscle fatigue Á Oxygen consumption Á Energy expenditure Á Plyometric push-up Á Isometric mid-thigh pull Á Counter-movement jump Abbreviations ANOVA Analysis of variance CMJ Counter-movement jump IMTP Isometric mid-thigh pull MET Metabolic equivalent WB-EMS Whole-body electromyostimulation The research was conducted at
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Papers by Lorenzo Bortolan