Energy cost of running uphill as compared to running on the level with impeding horizontal forces.

Purpose: We have previously shown that accelerated running on flat terrain is biomechanically equivalent to running uphill at a constant speed. This hypothesis was further investigated comparing the energy cost of running at a constant speed either uphill, or on flat terrain against an equivalent horizontal impeding force, mimicking acceleration.

Methods: Steady-state O consumption and the corresponding energy cost (per unit body mass and distance) were determined on 12 male subjects during treadmill running at speeds between 2.

Energy cost differences between marathon runners and soccer players: Constant versus shuttle running.

In the last decades, the energy cost assessment provided new insight on shuttle or constant running as training modalities. No study, though, quantified the benefit of constant/shuttle running in soccer-players and runners. Therefore, the aim of this study was to clarify if marathon runners and soccer players present specific energy cost values related to their training experience performing constant and shuttle running.

Sarcopenia parameters in active older adults - an eight-year longitudinal study.

Backgroud: Sarcopenia is a common skeletal muscle syndrome that is common in older adults but can be mitigated by adequate and regular physical activity. The development and severity of sarcopenia is favored by several factors, the most influential of which are a sedentary lifestyle and physical inactivity. The aim of this observational longitudinal cohort study was to evaluate changes in sarcopenia parameters, based on the EWGSOP2 definition in a population of active older adults after eight years.

A century of exercise physiology: key concepts on coupling respiratory oxygen flow to muscle energy demand during exercise.

After a short historical account, and a discussion of Hill and Meyerhof's theory of the energetics of muscular exercise, we analyse steady-state rest and exercise as the condition wherein coupling of respiration to metabolism is most perfect. The quantitative relationships show that the homeostatic equilibrium, centred around arterial pH of 7.4 and arterial carbon dioxide partial pressure of 40 mmHg, is attained when the ratio of alveolar ventilation to carbon dioxide flow ([Formula: see text]) is - 21.

Comfortable walking speed and energy cost of locomotion in patients with multiple sclerosis.

Comfortable walking speed and energy cost of walking are physiological markers of metabolic activity during gait. People with multiple sclerosis are characterized by altered gait biomechanics and energetics, related to the degree of disability and spasticity, which lead to an increased energy cost of walking. Several studies concerning the energy cost of walking in multiple sclerosis have been published.

Metabolic Power in Team Sports - Part 2: Aerobic and Anaerobic Energy Yields.

A previous approach to estimate the time course of instantaneous metabolic power and O consumption in team sports has been updated to assess also energy expenditure against air resistance and to identify walking and running separately. Whole match energy expenditure turned out ≈14% smaller than previously obtained, the fraction against the air resistance amounting to ≈2% of the total. Estimated net O consumption and overall energy expenditure are fairly close to those measured by means of a portable metabolic cart; the average difference, after a 45 min exercise period of variable intensity and mode, amounting to ≈10%.

Metabolic Power in Team Sports - Part 1: An Update.

Team sports are characterised by frequent episodes of accelerated/decelerated running. The corresponding energy cost can be estimated on the basis of the biomechanical equivalence between accelerated/decelerated running on flat terrain and constant speed running uphill/downhill. This approach allows one to: (i) estimate the time course of the instantaneous metabolic power requirement of any given player and (ii) infer therefrom the overall energy expenditure of any given time window of a soccer drill or match.

Effects of 14 days of bed rest and following physical training on metabolic cost, mechanical work, and efficiency during walking in older and young healthy males.

In this study, we investigated: i) the effects of bed rest and a subsequent physical training program on metabolic cost (Cw), mechanical work and efficiency during walking in older and young men; ii) the mechanisms underlying the higher Cw observed in older than young men.Twenty-three healthy male subjects (N = 16 older adults, age 59.6±3.

Effects of recovery interval duration on the parameters of the critical power model for incremental exercise.

Introduction: We tested the linear critical power ([Formula: see text]) model for discrete incremental ramp exercise implying recovery intervals at the end of each step.

Methods: Seven subjects performed incremental (power increment 25 W) stepwise ramps to subject's exhaustion, with recovery intervals at the end of each step. Ramps' slopes (S) were 0.

Greater loss in muscle mass and function but smaller metabolic alterations in older compared with younger men following 2 wk of bed rest and recovery.

This investigation aimed to compare the response of young and older adult men to bed rest (BR) and subsequent rehabilitation (R). Sixteen older (OM, age 55-65 yr) and seven young (YM, age 18-30 yr) men were exposed to a 14-day period of BR followed by 14 days of R. Quadriceps muscle volume (QVOL), force (QF), and explosive power (QP) of leg extensors; single-fiber isometric force (Fo); peak aerobic power (V̇o2peak); gait stride length; and three metabolic parameters, Matsuda index of insulin sensitivity, postprandial lipid curve, and homocysteine plasma level, were measured before and after BR and after R.

A 35-day bed rest does not alter the bilateral deficit of the lower limbs during explosive efforts.

Purpose: Bilateral deficit (BLD) occurs when the force (or power) generated by both limbs together is smaller than the sum of the forces (or powers) developed separately by the two limbs. The amount of BLD can be altered by neural adaptations brought about by the repetitive execution of specific motor tasks (training). Prolonged disuse also leads to relevant neural adaptations; however, its effects on BLD are still unknown.

Maximal explosive power of the lower limbs before and after 35 days of bed rest under different diet energy intake.

Purpose: Microgravity leads to a decline of muscle power especially in the postural muscles of the lower limb. Muscle atrophy primarily contributes to this negative adaptation. Nutritional countermeasures during unloading were shown to possibly mitigate the loss of muscle mass and strength.

Force-velocity properties' contribution to bilateral deficit during ballistic push-off.

Purpose: The objective of this study is to quantify the contribution of the force-velocity (F-v) properties to bilateral force deficit (BLD) in ballistic lower limb push-off and to relate it to individual F-v mechanical properties of the lower limbs.

Methods: The F-v relation was individually assessed from mechanical measurements for 14 subjects during maximal ballistic lower limb push-offs; its contribution to BLD was then investigated using a theoretical macroscopic approach, considering both the mechanical constraints of movement dynamics and the maximal external capabilities of the lower limb neuromuscular system.

Results: During ballistic lower limb push-off, the maximum force each lower limb can produce was lower during bilateral than unilateral actions, thus leading to a BLD of 36.

Optimal starting block configuration in sprint running; a comparison of biological and prosthetic legs.

In the 2012 Paralympic 100 m and 200 m finals, 86% of athletes with a unilateral amputation placed their unaffected leg on the front starting block. Can this preference be explained biomechanically? We measured the biomechanical effects of starting block configuration for seven nonamputee sprinters and nine athletes with a unilateral amputation. Each subject performed six starts, alternating between their usual and unusual starting block configurations.

The energy cost of shuttle running.

The aim of this study was to: (1) determine directly the energy cost of shuttle running (C Sh) and (2) compare it to the values indirectly estimated from kinematic data. C Sh over distances of ≈10 or ≈20 m was determined on 65 subjects (group 1) from gas exchange measurements over 155 trials, or indirectly estimated on 10 subjects (group 2) from the time course of the speed as follows. (1) The cost to accelerate from zero to peak speed was estimated assuming a 25 % efficiency and added to that of constant-speed running, as obtained on subjects of group 1.

Functional impairment of skeletal muscle oxidative metabolism during knee extension exercise after bed rest.

A functional evaluation of skeletal muscle oxidative metabolism during dynamic knee extension (KE) incremental exercises was carried out following a 35-day bed rest (BR) (Valdoltra 2008 BR campaign). Nine young male volunteers (age: 23.5 ± 2.

The energetics of ultra-endurance running.

Our objective was to determine the effects of long-lasting endurance events on the energy cost of running (C(r)), and the role of maximal oxygen uptake (VO(2max)), its fractional utilisation (F) and C(r) in determining the performance. Ten healthy runners (age range 26-59 years) participated in an ultra-endurance competition consisting of three running laps of 22, 48 and 20 km on three consecutive days in the North-East of Italy. Anthropometric characteristics and VO(2max) by a graded exercise test on a treadmill were determined 5 days before and 5 days after the competition.

Optimal force-velocity profile in ballistic movements--altius: citius or fortius?

Purpose: The study's purpose was to determine the respective influences of the maximal power (Pmax) and the force-velocity (F-v) mechanical profile of the lower limb neuromuscular system on performance in ballistic movements.

Methods: A theoretical integrative approach was proposed to express ballistic performance as a mathematical function of Pmax and F-v profile. This equation was (i) validated from experimental data obtained on 14 subjects during lower limb ballistic inclined push-offs and (ii) simulated to quantify the respective influence of Pmax and F-v profile on performance.

Energetics of best performances in elite kayakers and canoeists.

Purpose: The objectives of this study were 1) to validate a new test to determine maximal oxygen uptake (V˙O2max) in kayakers, 2) to calculate the energy cost (Ck) of high-level kayakers and canoeists at submaximal and race speeds, and 3) to correlate individual best performances achieved in practice with those theoretically calculated. These were obtained from the individual relationships Ėr=f(t) and Ėmax=f(t), where Ėr is the metabolic power required to cover the distance in question and Ėmax is the maximal metabolic power. The time yielding Ėr=Ėmax was assumed to yield the best performance time.

Energy cost and metabolic power in elite soccer: a new match analysis approach.

Purpose: Video match analysis is used for the assessment of physical performances of professional soccer players, particularly for the identification of "high intensities" considered as "high running speeds." However, accelerations are also essential elements setting metabolic loads, even when speed is low. We propose a more detailed assessment of soccer players' metabolic demands by video match analysis with the aim of also taking into account accelerations.

Bilateral deficit and EMG activity during explosive lower limb contractions against different overloads.

We investigated whether bilateral deficit (BLD): (1) is observed during explosive lower limb contractions; (2) can be attributed to a reduction of neural drive and/or (3) to a different muscle coordination, and/or (4) to changes of the muscle force-velocity (F-v) relationship. Ten volunteers performed maximal explosive efforts of approximately 450 ms on a sledge ergometer, with both lower limbs (BL), with the right and left limb separately (ML), against different overloads. Peak-force (F, N), peak-power (w, W), sledge peak-velocity (v, m/s) and electromyography (EMG) of vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF) and gastrocnemius medialis (GM) were recorded.

A simple method for assessing the energy cost of running during incremental tests.

The energy cost of running (Cr) is classically determined from steady-state oxygen consumption (Vo2) at constant speed, divided by running speed. In the present study, Cr was determined during incremental treadmill tests in the course of the assessment of Vo(2max) and related parameters as follows. Assume that the running speed is increased by a constant amount (Deltav) at regular short intervals (T) and that, during each intensity transient below the gas exchange threshold, Vo2 increases exponentially, without time delay, toward the steady state.

Sprint and endurance power and ageing: an analysis of master athletic world records.

Human physical performance is notably reduced with ageing. Although the effects of ageing are often compounded by disuse, the study of master athletes provides an opportunity for investigating the effects of ageing per se. It is often held that sprinting is more affected than endurance performance.

Influence of phosphagen concentration on phosphocreatine breakdown kinetics. Data from human gastrocnemius muscle.

At the onset of a square-wave exercise of moderate intensity, in the absence of any detectable lactate production, the hydrolysis of phosphocreatine (PCr) fills the gap between energy requirement and energy yield by oxidative pathways, thus representing a readily available source of energy for the muscle. We verified experimentally the relationships between high-energy phosphates and/or their changes and the time constant of PCr concentration ([PCr]) kinetics in humans (tau(PCr)). High-energy phosphate concentration (by (31)P-NMR spectroscopy) in the calf muscles were measured during three repetitions of the rest-to-work transition of moderate aerobic square-wave exercise on nine healthy volunteers, while resting [PCr] was estimated from the appropriate spectroscopy data.