Alessandro Rosponi

Exercise induced muscle damage and recovery assessed by means of linear and non-linear sEMG analysis and ultrasonography

This study was aimed at investigating the time-course and recovery from eccentric (EC) exercise induced muscle damage by means of surface electromyography (sEMG), ultrasonography (US), and blood enzymes. Five subjects (EC Group) performed two bouts of 35 EC maximum contractions with the biceps brachii of their non dominant arm, five subjects were tested without performing EC (Control Group: CNT). The maximal isometric force (MVC) was measured. Force and sEMG signals were recorded during 80% MVC isometric contractions. In EC and CNT subjects US assessment on non-dominant biceps brachii was performed; creatin kinase (CK) and lactic dehydrogenasis (LDH) plasma levels were also assessed. Force, sEMG and CK-LDH measurements were performed before EC and after it periodically for 4 weeks. The sEMG was analysed in time and frequency domains; a non-linear analysis (Lyapunov 1st exponent, L1) of sEMG was also performed. After EC, the MVC was reduced by 40% on average with respect to the pre-EC values. A significant decrease in the initial frequency content, and in the MDF and L1 decay (13-42% less than the pre-EC values, respectively) was also observed. The sEMG amplitude (Root Mean Square, RMS) was unchanged after EC. The US revealed an increase in muscle belly thickness and in local muscle blood flow after EC. A complete recovery of all the considered parameters was achieved in two weeks. In conclusion sEMG analysis was confirmed as an early indicator of muscle damage. Muscle recovery from damage is followed by both sEMG and US and this may have useful clinical implications. Non linear analysis (L1) was revealed to be sensitive to early sEMG modifications induced by EC as well as able to follow the post EC changes in the sEMG.

Differences in the force/endurance relationship between young and older men

The aim of the present study was to ascertain if in six young (23–35 years) and in six older (70–72 years) healthy men matched for comparable absolute and specific maximal force of the dominant elbow flexors, differences in isometric endurance, myoelectrical fatigability, and shortening velocity are still recognizable. To assess the specific force, the muscle cross sectional area (CSA) was determined from magnetic resonance imaging (MRI) scans. The performance of the elbow flexors was studied by assessing the isometric endurance times (ET) at different percentages of maximal isometric contraction (MVC), the average muscle fibre conduction velocity of action potentials (CV), and the median frequency (MDF) of the surface electromyogram (sEMG) of the biceps brachii. Finally, the torque-velocity curve was assessed by means of maximal isokinetic contractions at six fixed angular velocities. All data were expressed as the mean (SD). The results showed that: (1) the ET was longer in the older subjects at the highest levels of isometric contraction, independently from the absolute force; (2) the modifications of muscle fibre CV during isometric effort progressed less rapidly in the older than the younger groups, as did those of MDF; and (3) at the same angular velocity, the older subjects exerted less absolute force than the younger subjects. These results suggest an impairment of the neuromuscular system of older men, which is less powerful and less fatigable than that of young men.

Physiological adaptation in noncompetitive rock climbers: good for aerobic fitness?

The present investigation aimed to establish whether noncompetitive rock climbing fulfills sports medicine recommendations for maintaining a good level of aerobic fitness. The physiological profile of 13 rock climbers, 8 men (age, 43 ± 8 years) and 5 women (age, 31 ± 8 years) was assessed by means of laboratory tests. Maximal aerobic power (&OV0312;o2peak) and ventilatory threshold (VT) were assessed using a cycloergometer incremental test. During outdoor rock face climbing, &OV0312;o2 and heart rate (HR) were measured with a portable metabolimeter and the relative steady-state values (&OV0312;o2 and HR during rock climbing) were computed. Blood lactate was measured during recovery. All data are presented as mean ± SD. &OV0312;o2peak was 39.1 ± 4.3 mL·kg−1·min−1 in men and 39.7 ± 5 mL·kg−1·min−1 in women, while VT was 29.4 ± 3.0 mL·kg−1·min−1 in men and 28.8 ± 4.6 mL·kg−1·min−1 in women. The &OV0312;o2 during rock climbing was 28.3 ± 1.5 mL·kg−1·min−1 in men and 27.5 ± 3.7 mL·kg−1·min−1 in women. The HR during rock climbing was 144 ± 16 b·min−1 in men and 164 ± 13 b·min−1 in women. The aerobic profile was classified from excellent to superior in accordance with the standards of the American College of Sports Medicine (ACSM). The exercise intensity (&OV0312;o2 during rock climbing expressed as a percentage of &;o2peak) was 70 ± 6% in men and 72 ± 8% in women. Moreover, the energy expenditure was 1000-1500 kcal per week. In conclusion, noncompetitive rock climbing has proved to be a typical aerobic activity. The intensity of exercise is comparable to that recommended by the American College of Sports Medicine to maintain good cardiorespiratory fitness.

Forestry work in the Italians alps: metabolic demand assessed by heart rate

Objective : This research aims to: a) assess the energy expenditure during typical forestry activities; b) assess the actual workload of forestry work; c) define the eventual relationship between oxygen uptake ( ) and heart rate during the studied working phases. Methods : Eleven healthy skilled forestry workers were studied. Using a portable device, oxygen uptake ( ), carbon dioxide output ( ), pulmonary ventilation ( ) and heart rate (HR) were measured. The forestry work was divided into four phases: walking uphill, felling, limbing & chain-sawing and complementary activities. A work time report was kept and in each phase a weighted average (WA) of all parameters was obtained. Results :Walking uphill, felling, limbing & chain-sawing activities did not show significant statistical differences between each other and were classified as heavy activities (mean 2.17 lmin-1,mean HR 157 beatmin-1). The complementary activity was found to be less demanding and statistically differed in respect to the others ( 0.55 l min-1, HR 98 beat min-1). By theWA, the actual workload of forestry work resulted in a moderate to heavyoptimal job ( and HR being 1.51 l min-1 and 133.5 beat min-1 respectively in a typical working day). Furthermore it was possible to set up a relationship between and HR for the forestry work. Conclusions : Forestry activity can be classified as moderate to heavy-optimal. Finally, a good and linear correlation between and HR proved to be an easy tool to evaluate the metabolic demand.