Biomedical subjects

Andrea Macaluso

Publications and source records attributed to Andrea Macaluso.

10 recordsLinked to original sources

PubMed2006

Reliability of the intrinsic and extrinsic patterns of level walking in older women.

The aim of the study was to assess short- and long-term reliability of the harmonic analysis of the trajectories of head, upper trunk, and pelvis during walking in healthy older women, which reveals mechanisms to coordinate upper body segments and control head stability in the search for a safer gait. A stereophotogrammetric system was used to measure the displacement of markers located at head, shoulder, and pelvis level in 11 healthy older women (77+/-2 years) walking on an oval shaped 20-m walkway circuit, in three experimental sessions separated by 6 weeks. The harmonic analysis of the time-curves was highly reliable both within and between sessions (standard error of measurement ranging between 0.15 mm and 1.50mm for the amplitudes and 0.03 rad and 0.41 rad for the phases) and revealed different oscillatory patterns for the pelvis, head, and upper trunk. An intrinsic pattern, representing the natural overall movement symmetry of the whole population of older women of this study, was described by the first medio-lateral harmonic and second antero-posterior and vertical harmonics. An extrinsic pattern, characteristic of each individual in the population, was described by the first antero-posterior and vertical harmonics. The intrinsic pattern was both intra- and inter-subject repeatable (coefficient of multiple correlation, CMC, ranging between 0.82 and 0.99), while the extrinsic pattern was only intra-subject repeatable (CMC ranging between 0.70 and 0.90). Harmonic analysis reliably describes upper body kinematics in older women for detecting the intrinsic and extrinsic patterns of gait, which reveal fundamental mechanisms governing their walking.

Aged↗

PubMed2006

Correlation of average muscle fiber conduction velocity measured during cycling exercise with myosin heavy chain composition, lactate threshold, and VO2max.

The aim of the study was to investigate the correlation between myosin heavy chain (MHC) composition, lactate threshold (LT), maximal oxygen uptake VO2max, and average muscle fiber conduction velocity (MFCV) measured from surface electromyographic (EMG) signals during cycling exercise. Ten healthy male subjects participated in the study. MHC isoforms were identified from a sample of the vastus lateralis muscle and characterized as type I, IIA, and IIX. At least three days after a measure of LT and VO2max, the subjects performed a 2-min cycling exercise at 90 revolutions per minute and power output corresponding to LT, during which surface EMG signals were recorded from the vastus lateralis muscle with an adhesive electrode array. MFCV and instantaneous mean power spectral frequency of the surface EMG were estimated at the maximal instantaneous knee angular speed. Output power corresponding to LT and VO2max were correlated with percentage of MHC I (R2=0.77; and 0.42, respectively; P<0.05). MFCV was positively correlated with percentage of MHC I, power corresponding to LT and to VO2max (R2=0.84; 0.74; 0.53, respectively; P<0.05). Instantaneous mean power spectral frequency was not correlated with any of these variables or with MFCV, thus questioning the use of surface EMG spectral analysis for indirect estimation of MFCV in dynamic contractions.

Adult↗

PubMed2004

Effect of power, pedal rate, and force on average muscle fiber conduction velocity during cycling.

Muscle fiber conduction velocity (MFCV) provides indications on motor unit recruitment strategies due to the relation between conduction velocity and fiber diameter. The aim of this study was to investigate MFCV of thigh muscles during cycling at varying power outputs, pedal rates, and external forces. Twelve healthy male participants aged between 19 and 30 yr cycled on an electronically braked ergometer at 45, 60, 90, and 120 rpm. For each pedal rate, subjects performed two exercise intensities, one at an external power output corresponding to the previously determined lactate threshold (100% LT) and the other at half of this power output (50% LT). Surface electromyogram signals were detected during cycling from vastus lateralis and medialis muscles with linear adhesive arrays of eight electrodes. In both muscles, MFCV was higher at 100% LT compared with 50% LT for all average pedal rates except 120 rpm (mean +/- SE, 4.98 +/- 0.19 vs. 4.49 +/- 0.18 m/s; P < 0.001). In all conditions, MFVC increased with increasing instantaneous knee angular speed (from 4.14 +/- 0.16 to 5.08 +/- 0.13 m/s in the range of instantaneous angular speeds investigated; P < 0.001). When MFCV was compared at the same external force production (i.e., 90 rpm/100% LT vs. 45 rpm/50% LT, and 120 rpm/100% LT vs. 60 rpm/50% LT), MFCV was higher at the faster pedal rate (5.02 +/- 0.17 vs. 4.64 +/- 0.12 m/s, and 4.92 +/- 0.19 vs. 4.49 +/- 0.11 m/s, respectively; P < 0.05) due to the increase in inertial power required to accelerate the limbs. It was concluded that, during repetitive dynamic movements, MFCV increases with the external force developed, instantaneous knee angular speed, and average pedal rate, indicating progressive recruitment of large, high conduction velocity motor units with increasing muscle force.

Adult↗

PubMed2004

Differences between young and older women in maximal force, force fluctuations, and surface EMG during isometric knee extension and elbow flexion.

The loss of muscle strength with aging appears to be greater in the lower than upper limbs, but strength and its neural control have never been compared in the same population of individuals in both upper and lower limbs. The aim of this study was to investigate differences between eight young (20-31 years) and eight older (68-76 years) healthy women in maximal voluntary contraction (MVC), force fluctuations, median frequency (MDF) of the surface electromyogram (sEMG), and muscle fiber conduction velocity (MFCV) during sustained isometric elbow flexion (EF) and knee extension (KE), performed at moderate to high force intensity. Older women showed larger fluctuations of force with endurance and changes in sEMG pointing to less fatigue, especially at high level of force, with no differences between upper and lower extremities. This may have significant implications in the design of rehabilitation programs directed to this population.

Adult↗

PubMed2003

Muscle strength, power and adaptations to resistance training in older people.

Muscle strength and, to a greater extent, power inexorably decline with ageing. Quantitative loss of muscle mass, referred to as "sarcopenia", is the most important factor underlying this phenomenon. However, qualitative changes of muscle fibres and tendons, such as selective atrophy of fast-twitch fibres and reduced tendon stiffness, and neural changes, such as lower activation of the agonist muscles and higher coactivation of the antagonist muscles, also account for the age-related decline in muscle function. The selective atrophy of fast-twitch fibres has been ascribed to the progressive loss of motoneurons in the spinal cord with initial denervation of fast-twitch fibres, which is often accompanied by reinnervation of these fibres by axonal sprouting from adjacent slow-twitch motor units (MUs). In addition, single fibres of older muscles containing myosin heavy chains of both type I and II show lower tension and shortening velocity with respect to the fibres of young muscles. Changes in central activation capacity are still controversial. At the peripheral level, the rate of decline in parameters of the surface-electromyogram power spectrum and in the action-potential conduction velocity has been shown to be lower in older muscle. Therefore, the older muscle seems to be more resistant to isometric fatigue (fatigue-paradox), which can be ascribed to the selective atrophy of fast-twitch fibres, slowing in the contractile properties and lower MU firing rates. Finally, specific training programmes can dramatically improve the muscle strength, power and functional abilities of older individuals, which will be examined in the second part of this review.

Adaptation, Physiological↗

PubMed2003

Cycling as a novel approach to resistance training increases muscle strength, power, and selected functional abilities in healthy older women.

Cycling on a mechanically braked cycle ergometer was used as a novel approach to compare the effects of three different 16-wk resistance-training programs on isometric force, power output, and selected functional abilities in 31 healthy 65- to 74-yr-old women. Training was conducted three times per week. During each session, individuals of the speed group performed 8 sets of 16 pedal revolutions at 40% of the maximal resistance to complete two revolutions (2 RM); strength group performed 8 sets of 8 revolutions at 80% of 2 RM; and combination group performed 4 sets of 16 revolutions at 40% and 4 sets of 8 revolutions at 80% of 2 RM. During each set, all participants were required to pedal as fast as possible with a 2-min interval between sets. All training groups significantly increased force, power, and functional abilities (maximal treadmill walking speed, vertical jumping, and box stepping) at week 8 (in the range from 6.5 to 20.8%) with no further improvement at week 16 (except maximal treadmill walking speed), but no significant differences were observed between the three groups. The novel approach to performing both low- and high-resistance training, based on the use of a cycle ergometer, has been shown to be effective in improving strength, power, and functional abilities in a group of healthy women. Even fit older women can still improve in functional abilities. Interestingly, the "high-speed" and "low-speed" programs induced an increase in both power and strength of similar magnitude.

Adaptation, Physiological↗

PubMed2003

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load.

Lower limb explosive power, which is more predictive of functional difficulties than strength per se with women being more at risk than men for disability, has been previously compared between young and older women using systems with fixed inertia. Individuals may have been obliged to use a percentage of their maximum strength that is not ideal for performing the movement at the optimum speed for maximum power output. This study was designed to compare explosive power output and its two determinants, optimal force and optimal speed, during a leg-press action between young and older women after optimising the load for maximum power production. The experiments were carried out on 20 women in good physical condition: 10 older, aged between 65 and 74 years and 10 young, aged between 18 and 30. Explosive power output was measured by setting the initial load at different percentages of maximum isometric strength and measuring the corresponding speed of movement during a leg-press action of the dominant leg. Maximum peak power, which was obtained at 60% of maximum isometric strength in both young and older women, was 61% lower in the older women ( P<0.0001). This was due to a 52% lower optimal force ( P<0.0001) and 21% lower optimal speed ( P<0.01). The ratio of peak power to maximum isometric strength was 22.1% lower in the older women ( P<0.01). After optimising the load, both lower speed of movement and lower strength determine the lower levels of power in older women. Power is more affected by ageing than isometric strength.

Adolescent↗

PubMed2003

The effect of an active warm-up on surface EMG and muscle performance in healthy humans.

The effect of an active warm-up on maximal voluntary contraction (MVC), maximal instantaneous power output and surface EMG (sEMG) parameters was studied. Eight volunteers [mean (SD) 22 (4) years] completed two trials on the same day, one control (CO), and the other preceded by an active cycling warm-up (WU) at 70% ventilatory threshold determined by the ventilatory equivalent method. Quadriceps muscle temperature, measured from vastus lateralis with a flexible thermistor, was 33.8 (0.4) degrees C in CO compared to 36.8 (0.5) degrees C in WU ( P<0.05). Aural temperature, measured by an infrared tympanic thermistor, was not different between conditions. Experimental trials consisted of three knee-extension maximum voluntary contractions at a 90 degree angle with simultaneous recording of sEMG from the vastus lateralis, followed by three squat jumps performed on a force platform. SEMGs were analysed in the frequency domain as median frequency (MDF) and in the time domain as root mean square (RMS). MDF was 59.2 (14.1) Hz in CO compared to 67.2 (11.8) Hz in WU ( P<0.05), while RMS was higher in CO compared to WU [0.65 (0.28) mV vs. 0.56 (0.19) mV; P<0.05]. MVC was not different [465.7 (107.6) N vs. 490.1 (117.2) N], whilst instantaneous power output during the squat jump was significantly higher in the WU trial [3324 (866) W vs. 3569 (919) W; P<0.05]. These data show MDF to be altered with an active warm-up, which would relate to a greater conduction velocity. This may translate into faster activation of the muscle fibres, thus partly explaining the increase in power output.

Adult↗

PubMed2002

Contractile muscle volume and agonist-antagonist coactivation account for differences in torque between young and older women.

It is controversial whether specific tension (the ratio between muscle strength and size) declines with aging. Therefore, contractile muscle volume was estimated separately from the intramuscular noncontractile tissue by magnetic resonance imaging, and maximum isometric torque was measured in the knee extensors and flexors of 10 young (22.8 +/- 5.7 years) and 10 older (69.5 +/- 2.4 years) healthy active women. Specific tension was lower in the older women both in the extensors (93.1 +/- 20.1 kN x m(-2) vs. 112.1 +/- 12.3 kN x m(-2); P < 0.05) and in the flexors (100 +/- 31 kN x m(-2) vs. 142.7 +/- 23.9 kN x m(-2); P < 0.01). This was accompanied by an increase in the percentage coactivation of the knee flexors during knee extension. These data suggest that the lower level of muscle torque in the older women can be explained not only by smaller contractile muscle mass but also by increased coactivation of the antagonist muscles during knee extension.

Adult↗

PubMed2002

Muscle function in elite master weightlifters.

PURPOSE: To determine whether explosive power and isometric strength of the lower-limb muscles in elite master Olympic weightlifters declines at a similar rate to nontrained healthy controls with increasing age. METHODS: 54 elite level masters weightlifters (aged 40-87), who were competitors at the World Masters Weightlifting Championships (1999), were compared with a similar number of aged-matched, healthy untrained individuals. Isometric knee extensor strength and lower-limb explosive power were tested. Extent of antagonist co-contraction during isometric knee extension was determined by EMG and power loading characteristics by using a variable inertial system. Muscle volume was estimated using anthropometry. RESULTS: On average, the weightlifters were able to generate 32% more peak power (P < 0.05) in the lower limbs and 32% more isometric knee extensor force (P < 0.05) than the control subjects. No significant differences in lower-leg volume were observed between the two groups. Peak power declined at a similar rate with increasing age in the weightlifters and controls (1.2 and 1.3% of a 45-yr-old's value per year), as did strength, but at a lower rate (0.6 and 0.5% per year). The inertial load at which the weightlifters achieved their maximal peak power output was greater (P < 0.05) than the controls. The torque generated at this optimal inertia was also greater in the weightlifters (P < 0.05), whereas the time taken for the weightlifters to reach their maximal peak power was on average 13% shorter (P < 0.05). No differences in antagonist co-contraction during isometric knee extension were observed between the two groups. CONCLUSIONS: Muscle power and isometric strength decline at a similar rate with increasing age in elite master weightlifters and healthy controls. In spite of inertial load optimization, muscle power declined in both groups at approximately twice the rate of isometric strength. Although similar rates of decline were observed, the absolute differences between the weightlifters and controls were such that an 85-yr-old weightlifter was as powerful as a 65-yr-old control subject. This would therefore represent an apparent age advantage of approximately 20 yr for the weightlifters.

Adult↗