Martina Anna Maggioni

Body composition assessment in spinal cord injury subjects.

Abstract.Total and segmental body composition (fat mass, FM; fat-free mass, FFM; bone mineral density, BMD) were evaluated in 13 sedentary spinal cord injury (SCI) subjects and in 13 able-bodied healthy males (control, C) using dual X-ray absorptiometry (DXA) and skinfold methods. In the SCI group, total FM was significantly higher (31.1±8.2 vs. 20.8±6.9%) and total FFM was significantly lower (62.2±8.9 vs. 73.5±6.4%) than in C subjects. Total BMD did not differ between the SCI and C groups (1.20±0.11 vs. 1.30±0.11 g/cm2). In the SCI group, segmental FM was higher in the legs and trunk, whereas BMD was lower in legs only. The skinfold method significantly underestimated FM in the SCI group. Body composition is severely modified in paralyzed segments. The predictive equations developed for healthy populations appear to be inapplicable to SCI subjects.

Effects of passive stretching on post-activation potentiation and fibre conduction velocity of biceps brachii muscle

Stretching is usually part of warm-up routines in many sports, but it affects the subsequent muscle force; therefore, it could negatively influence post-activation potentiation (PAP), one of the warm-up’s main effects. The aim of this study was to evaluate the acute effects of passive stretching on PAP and fibre conduction velocity (CV). Seven subjects underwent 2 experimental sessions, control (C) and stretching (S), each consisting of 2 series (7 min resting) of 3 maximal voluntary contractions (MVC) of biceps brachii (5 s isometric contraction, 10 s recovery). During the resting phase of the S session, the biceps brachii was passively stretched (5×45 s stretches, 15 s recovery). Root mean square (RMS), mean frequency (MF) and CV were calculated from electromyography. Peak torque (pT) and half-contraction time (1/2CT) were measured and normalised by the arm muscular area (pTn). After C, pTn increased and 1/2CT decreased (p<0.05); moreover, MF and CV increased (p<0.05). After S, 1/2CT increased (p<0.05) and RMS decreased (p<0.05). Passive stretching could blunt the effects of PAP, presumably due to mechanical and neuromuscular changes. The observed changes in CV suggest a possible decrease in Ca2+ sensitivity in contractile proteins. Therefore, the use of passive stretching in warm-up routines remains questionable.

Stretching and deep and superficial massage do not influence blood lactate levels after heavy-intensity cycle exercise.

Abstract The study aimed to assess the role of deep and superficial massage and passive stretching recovery on blood lactate concentration ([La−]) kinetics after a fatiguing exercise compared to active and passive recovery. Nine participants (age 23 ± 1 years; stature 1.76 ± 0.02 m; body mass 74 ± 4 kg) performed on five occasions an 8-min fatiguing exercise at 90% of maximum oxygen uptake, followed by five different 10-min interventions in random order: passive and active recovery, deep and superficial massage and stretching. Interventions were followed by 1 hour of recovery. Throughout each session, maximum voluntary contraction (MVC) of the knee extensor muscles, [La−], cardiorespiratory and metabolic variables were determined. Electromyographic signal (EMG) from the quadriceps muscles was also recorded. At the end of the fatiguing exercise, [La−], MVC, EMG amplitude, and metabolic and cardiorespiratory parameters were similar among conditions. During intervention administration, [La−] was lower and metabolic and cardiorespiratory parameters were higher in active recovery compared to the other modalities (P < 0.05). Stretching and deep and superficial massage did not alter [La−] kinetics compared to passive recovery. These findings indicate that the pressure exerted during massage administration and stretching manoeuvres did not play a significant role on post-exercise blood La− levels.

Heart adaptations to long-term aerobic training in paraplegic subjects : an echocardiographic study

Study design:Case–control.Objectives:To execute an echocardiographic comparison between trained and untrained spinal cord injury (SCI) subjects, and to evaluate whether long-term heart adjustments to endurance training are comparable to those observed in able-bodied (ABL) subjects.Setting:Italy.Methods:We enrolled: (1) 17 male SCI patients (lesion level T1–L3, 34±8 years, body mass index (BMI) 23.0±2.8 kg m−2), 10 of whom were aerobically trained for >5 years (SCIT); (2) 18 age-, sex- and BMI-matched ABL subjects (35±6 years, BMI 23.6±2.8 kg m−2), 10 of whom were aerobically trained for >5 years (ABLT). Training frequency and volume were recorded by a dedicated questionnaire. All subjects underwent a trans-thoracic echocardiography; SCI subjects also performed an exhaustive incremental exercise test. Comparisons were made between ABL and SCI groups, between trained and untrained subjects within each group (analysis of variance).Results:Effects of SCI—Compared with ABL subjects, SCI patients showed lower end-diastolic volume (76±21 vs 113±23 ml, P<0.05) and ejection fraction (61±7% vs 65±5%, P<0.05). Effects of training—Compared with untrained status, the intra-ventricular septum thickness (SCI, +18%; ABL, +4%), the posterior wall thickness (SCI, +17%; ABL, +2%) and the total normalized heart mass (SCI, +48%; ABL, +5%) were higher in both SCIT and in ABLT. VO2peak was higher in the SCIT subgroup compared with the SCIU group.Conclusions:Heart seems to positively adapt to long-term endurance training in SCI patients. Regular exercise may therefore increase heart size, septum and posterior wall thickness, which likely contributes to improved VO2peak. These morphological and functional changes may reduce cardiovascular risk in SCI individuals.

Circadian rhythms in bed rest: Monitoring core body temperature via heat-flux approach is superior to skin surface temperature

ABSTRACT Continuous recordings of core body temperature (CBT) are a well-established approach in describing circadian rhythms. Given the discomfort of invasive CBT measurement techniques, the use of skin temperature recordings has been proposed as a surrogate. More recently, we proposed a heat-flux approach (the so-called Double Sensor) for monitoring CBT. Studies investigating the reliability of the heat-flux approach over a 24-hour period, as well as comparisons with skin temperature recordings, are however lacking. The first aim of the study was therefore to compare rectal, skin, and heat-flux temperature recordings for monitoring circadian rhythm. In addition, to assess the optimal placement of sensor probes, we also investigated the effect of different anatomical measurement sites, i.e. sensor probes positioned at the forehead vs. the sternum. Data were collected as part of the Berlin BedRest study (BBR2-2) under controlled, standardized, and thermoneutral conditions. 24-hours temperature data of seven healthy males were collected after 50 days of -6° head-down tilt bed-rest. Mean Pearson correlation coefficients indicated a high association between rectal and forehead temperature recordings (r > 0.80 for skin and Double Sensor). In contrast, only a poor to moderate relationship was observed for sensors positioned at the sternum (r = -0.02 and r = 0.52 for skin and Double Sensor, respectively). Cross-correlation analyses further confirmed the feasibility of the forehead as a preferred monitoring site. The phase difference between forehead Double Sensor and rectal recordings was not statistically different from zero (p = 0.313), and was significantly smaller than the phase difference between forehead skin and rectal temperatures (p = 0.016). These findings were substantiated by cosinor analyses, revealing significant differences for mesor, amplitude, and acrophase between rectal and forehead skin temperature recordings, but not between forehead Double Sensor and rectal temperature measurements. Finally, Bland-Altman analysis indicated narrower limits of agreement for rhythm parameters between rectal and Double Sensor measurements compared to between rectal and skin recordings, irrespective of the measurement site (i.e. forehead, sternum). Based on these data we conclude that (1) Double Sensor recordings are significantly superior to skin temperature measurements for non-invasively assessing the circadian rhythm of rectal temperature, and (2) temperature rhythms from the sternum are less reliable than from the forehead. We suggest that forehead Double Sensor recordings may provide a surrogate for rectal temperature in circadian rhythm research, where constant routine protocols are applied. Future studies will be needed to assess the sensor’s ecological validity outside the laboratory under changing environmental and physiological conditions.

Electrical stimulation versus kinesitherapy in improving functional fitness in older women: a randomized controlled trial.

Long-stay hospitalized elderly patients frequently develop a decrease in strength, cardiovascular fitness and balance, which can be improved by exercise. Neuromuscular electrical stimulation (ES) might also be effective in this population. The effect of different lower limb rehabilitation programs (3 interventions/week for 6 weeks) on functional fitness in 40 hospitalized old females (82+/-7 years) were evaluated: kinesitherapy (KT), ES, KT alternated with ES (KT+ES), and no treatment (C). Outcome variables after rehabilitation were: (a) maximal strength of leg extensor and finger flexor muscles; (b) cardiorespiratory fitness (6-min walking test, 6MWT; heart rate, HR); (c) static and dynamic balance and gait skills (Tinetti test). The maximal strength of leg extensor (but not finger flexor) muscles significantly improved in ES (+26%) and KT+ES (+16%) groups only. The distance covered during the 6MWT significantly increased in KT (+15%), ES (+14%) and KT+ES (+9%) groups, but the post-test HR recovery improved in KT group only. Balance (but not gait) skill scores significantly and similarly increased in KT (+11%), ES (+10%) and KT+ES (+11%) groups. In long-stay hospitalized old females ES and KT+ES improved lower limbs isometric strength. Walking ability was improved by all treatments, whereas cardiovascular performance and recovery were ameliorated by KT only.

Wearable Multi-Frequency and Multi-Segment Bioelectrical Impedance Spectroscopy for Unobtrusively Tracking Body Fluid Shifts during Physical Activity in Real-Field Applications: A Preliminary Study

Bioelectrical Impedance Spectroscopy (BIS) allows assessing the composition of body districts noninvasively and quickly, potentially providing important physiological/clinical information. However, neither portable commercial instruments nor more advanced wearable prototypes simultaneously satisfy the demanding needs of unobtrusively tracking body fluid shifts in different segments simultaneously, over a broad frequency range, for long periods and with high measurements rate. These needs are often required to evaluate exercise tests in sports or rehabilitation medicine, or to assess gravitational stresses in aerospace medicine. Therefore, the aim of this work is to present a new wearable prototype for monitoring multi-segment and multi-frequency BIS unobtrusively over long periods. Our prototype guarantees low weight, small size and low power consumption. An analog board with current-injecting and voltage-sensing electrodes across three body segments interfaces a digital board that generates square-wave current stimuli and computes impedance at 10 frequencies from 1 to 796 kHz. To evaluate the information derivable from our device, we monitored the BIS of three body segments in a volunteer before, during and after physical exercise and postural shift. We show that it can describe the dynamics of exercise-induced changes and the effect of a sit-to-stand maneuver in active and inactive muscular districts separately and simultaneously.

Explosive strength in female 11-on-11 versus 7-on-7 soccer players

Lower limbs strength capacity in female soccer players is poorly addressed. The aim of this study was to evaluate explosive strength in 7-on-7 (7FP) and 11-on-11 (11FP) female players and its possible changes at 3 different checkpoints of the competitive season. Thirteen 11FP of mean age 22.0 years) and twenty-six 7FP (of mean age 23.6 years) were enrolled. Vertical jump capacity was determined by means of squat jump (SJ) and counter movement jump (CMJ) tests in 3 different periods (September 2005, December 2005, April 2006). No significant differences were observed in SJ elevation or CMJ elevation between the two groups at any time point, and there were no significant changes over time. However, 7FPs tended to have higher explosive performance during SJ compared to 11FPs, and they had a significantly lower elastic recoil index at all three evaluations. This may be due to the characteristics of 7-on-7 soccer, in which the neuromuscular and explosive strength demands are higher than those of 11-on-11 soccer. Such requirements, though increasing muscular explosive performance, also increase the rigidity of the lower limb extensor apparatus.

Sleep Quality Changes during Overwintering at the German Antarctic Stations Neumayer II and III: The Gender Factor.

Purpose Antarctic residence holds many challenges to human physiology, like increased psycho-social tension and altered circadian rhythm, known to influence sleep. We assessed changes in sleep patterns during 13 months of overwintering at the German Stations Neumayer II and III from 2008 to 2014, with focus on gender, as many previous investigations were inconclusive regarding gender-based differences or had only included men. Materials & Methods Time in bed, sleep time, sleep efficiency, number of arousals, sleep latency, sleep onset, sleep offset, and physical activity level were determined twice per month during seven overwintering campaigns of n = 54 participants (37 male, 17 female) using actimetry. Data were analyzed using polynomial regression and analysis of covariance for change over time with the covariates gender, inhabited station, overwintering season and influence of physical activity and local sunshine radiation. Results We found overall longer times in bed (p = 0.004) and sleep time (p = 0.014) for women. The covariate gender had a significant influence on time in bed (p<0.001), sleep time (p<0.001), number of arousals (p = 0.04), sleep latency (p = 0.04), and sleep onset (p<0.001). Women separately (p = 0.02), but not men (p = 0.165), showed a linear increase in number of arousals. Physical activity decreased over overwintering time for men (p = 0.003), but not for women (p = 0.174). The decline in local sunshine radiation led to a 48 minutes longer time in bed (p<0.001), 3.8% lower sleep efficiency (p<0.001), a delay of 32 minutes in sleep onset (p<0.001), a delay of 54 minutes in sleep offset (p<0.001), and 11% less daily energy expenditure (p<0.001), for all participants in reaction to the Antarctic winter’s darkness-phase. Conclusions Overwinterings at the Stations Neumayer II and III are associated with significant changes in sleep patterns, with dependences from overwintering time and local sunshine radiation. Gender appears to be an influence, as women showed a declining sleep quality, despite that their physical activity remained unchanged, suggesting other causes such as a higher susceptibility to psycho-social stress and changes in environmental circadian rhythm during long-term isolation in Antarctica.

Interpretation and perception of slow, moderate, and fast swimming paces in distance and sprint swimmers.

This study assessed how accurately professional swimmers can interpret instructions to swim “slow,” “moderate,” and “fast.” 8 distance swimmers (6 males, 2 females; M age = 19 yr., SD = 3) and 8 sprint swimmers (7 males, 1 female; M age = 18yr., SD = 1) performed an all-out 50-m crawl stroke and three sets of 8 × 50-m crawl stroke trials interpreting the coachs instruction to swim at slow, moderate, and fast paces. No differences were detected between groups in absolute speed. Nevertheless, distance and sprint swimmers significantly differed in speed normalized to their own 50-m all-out speed (effect sizes = 6.72, 6.20, 1.35 for slow, moderate, and fast, respectively), stroke frequency (effect sizes = 0.81, 1.12, 1.54, respectively), and blood lactate concentration (effect sizes = 0.99, 2.56, 1.70, respectively).