Feasibility, acceptability and validation of wearable devices for climate change and health research in the low-resource contexts of Burkina Faso and Kenya: Study protocol

As the epidemiological transition progresses throughout sub-Saharan Africa, life lived with diseases is an increasingly important part of a population's burden of disease. The burden of disease of climate-sensitive health outcomes is projected to increase considerably within the next decades. Objectively measured, reliable population health data is still limited and is primarily based on perceived illness from recall. Technological advances like non-invasive, consumer-grade wearable devices may play a vital role in alleviating this data gap and in obtaining insights on the disease burden in vulnerable populations, such as heat stress on human cardiovascular response. The overall goal of this study is to investigate whether consumer-grade wearable devices are an acceptable, feasible and valid means to generate data on the individual level in low-resource contexts. Three hundred individuals are recruited from the two study locations in the Nouna health and demographic surveillance system (HDSS), Burkina Faso, and the Siaya HDSS, Kenya. Participants complete a structured questionnaire that comprises question items on acceptability and feasibility under the supervision of trained data collectors. Validity will be evaluated by comparing consumer-grade wearable devices to research-grade devices. Furthermore, we will collect demographic data as well as the data generated by wearable devices. This study will provide insights into the usage of consumer-grade wearable devices to measure individual vital signs in low-resource contexts, such as Burkina Faso and Kenya. Vital signs comprising activity (steps), sleep (duration, quality) and heart rate (hr) are important measures to gain insights on individual behavior and activity patterns in low-resource contexts. These vital signs may be associated with weather variables-as we gather them from weather stations that we have setup as part of this study to cover the whole Nouna and Siaya HDSSs-in order to explore changes in behavior and other variables, such as activity, sleep, hr, during extreme weather events like heat stress exposure. Furthermore, wearable data could be linked to health outcomes and weather events. As a result, consumer-grade wearables may serve as a supporting technology for generating reliable measurements in low-resource contexts and investigating key links between weather occurrences and health outcomes. Thus, wearable devices may provide insights to better inform mitigation and adaptation interventions in these low-resource settings that are direly faced by climate change-induced changes, such as extreme weather events.

Measuring Core Body Temperature Using a Non-invasive, Disposable Double-Sensor During Targeted Temperature Management in Post-cardiac Arrest Patients

Background: Precisely measuring the core body temperature during targeted temperature management after return of spontaneous circulation is mandatory, as deviations from the recommended temperature might result in side effects such as electrolyte imbalances or infections. However, previous methods are invasive and lack easy handling. A disposable, non-invasive temperature sensor using the heat flux approach (Double Sensor), was tested against the standard method: an esophagus thermometer.

Methods: The sensor was placed on the forehead of adult patients (n = 25, M/F, median age 61 years) with return of spontaneous circulation after cardiac arrest undergoing targeted temperature management. The recorded temperatures were compared to the established measurement method of an esophageal thermometer. A paired t-test was performed to examine differences between methods. A Bland-Altman-Plot and the intraclass correlation coefficient were used to assess agreement and reliability. To rule out possible influence on measurements, the patients' medication was recorded as well.

Results: Over the span of 1 year and 3 months, data from 25 patients were recorded. The t-test showed no significant difference between the two measuring methods (t = 1.47, p = 0.14, n = 1,319). Bland-Altman results showed a mean bias of 0.02°C (95% confidence interval 0.00–0.04) and 95% limits of agreement of −1.023°C and 1.066°C. The intraclass correlation coefficient was 0.94. No skin irritation or allergic reaction was observed where the sensor was placed. In six patients the bias differed noticeably from the rest of the participants, but no sex-based or ethnicity-based differences could be identified. Influences on the measurements of the Double Sensor by drugs administered could also be ruled out.

Conclusions: This study could demonstrate that measuring the core body temperature with the non-invasive, disposable sensor shows excellent reliability during targeted temperature management after survived cardiac arrest. Nonetheless, clinical research concerning the implementation of the sensor in other fields of application should be supported, as well as verifying our results by a larger patient cohort to possibly improve the limits of agreement.

Head-Down Tilt Position, but Not the Duration of Bed Rest Affects Resting State Electrocortical Activity

Adverse cognitive and behavioral conditions and psychiatric disorders are considered a critical and unmitigated risk during future long-duration space missions (LDSM). Monitoring and mitigating crew health and performance risks during these missions will require tools and technologies that allow to reliably assess cognitive performance and mental well-being. Electroencephalography (EEG) has the potential to meet the technical requirements for the non-invasive and objective monitoring of neurobehavioral conditions during LDSM. Weightlessness is associated with fluid and brain shifts, and these effects could potentially challenge the interpretation of resting state EEG recordings. Head-down tilt bed rest (HDBR) provides a unique spaceflight analog to study these effects on Earth. Here, we present data from two long-duration HDBR experiments, which were used to systematically investigate the time course of resting state electrocortical activity during prolonged HDBR. EEG spectral power significantly reduced within the delta, theta, alpha, and beta frequency bands. Likewise, EEG source localization revealed significantly lower activity in a broad range of centroparietal and occipital areas within the alpha and beta frequency domains. These changes were observed shortly after the onset of HDBR, did not change throughout HDBR, and returned to baseline after the cessation of bed rest. EEG resting state functional connectivity was not affected by HDBR. The results provide evidence for a postural effect on resting state brain activity that persists throughout long-duration HDBR, indicating that immobilization and inactivity per se do not affect resting state electrocortical activity during HDBR. Our findings raise an important issue on the validity of EEG to identify the time course of changes in brain function during prolonged HBDR, and highlight the importance to maintain a consistent body posture during all testing sessions, including data collections at baseline and recovery.

Reduced vagal modulations of heart rate during overwintering in Antarctica

Long-duration Antarctic expeditions are characterized by isolation, confinement, and extreme environments. Here we describe the time course of cardiac autonomic modulation assessed by heart rate variability (HRV) during 14-month expeditions at the German Neumayer III station in Antarctica. Heart rate recordings were acquired in supine position in the morning at rest once before the expedition (baseline) and monthly during the expedition from February to October. The total set comprised twenty-five healthy crewmembers (n = 15 men, 38 ± 6 yrs, n = 10 women, 32 ± 6 yrs, mean ± SD). High frequency (HF) power and the ratio of low to high frequency power (LF/HF) were used as indices of vagal modulation and sympathovagal balance. HF power adjusted for baseline differences decreased significantly during the expedition, indicating a gradual reduction in vagal tone. LF/HF powers ratio progressively shifted toward a sympathetic predominance reaching statistical significance in the final trimester (August to October) relative to the first trimester (February to April). This effect  was particularly pronounced in women. The depression of cardio-vagal tone and the shift toward a sympathetic predominance observed throughout the overwintering suggest a long-term cardiac autonomic modulation in response to isolation and confinement during Antartic overwintering.

Heart Rate Variability, Risk-Taking Behavior and Resilience in Firefighters During a Simulated Extinguish-Fire Task

Firefighters face a high-risk potential, thus their psychological ability to cope with critical or traumatic events is a crucial characteristic. This study examines correlations between cardiac autonomic modulation, risk-taking behavior, and resilience in professional firefighters. Twenty male professional firefighters underwent a 20 min beat-to-beat heart rate (HR) monitoring at baseline in the morning upon awakening, then before, during and after a realistic deployment in a container, systematically set on fire. Risk-taking behavior, resilience, and subjective stress were assessed by specific validated tools after deployment: the Risk-taking Scale (R-1), the Resilience Scale (RS-13), and the multi-dimensional NASA-Task Load Index. The cardiac autonomic modulation at rest and in response to stress was assessed by classic indexes of heart rate variability (HRV) as RMSSD and LF/HF ratio. Results showed that: (i) risk-taking behavior correlated with a withdrawal in vagal indices, shifted the baseline sympathovagal balance toward sympathetic predominance (LF/HF ratio r(8) = 0.522, p = 0.01), and increased mean HR both in baseline and during physical exercise (r(8) = 0.526, p = 0.01 and r(8) = 0.445, p = 0.05, respectively); (ii) resilience was associated with higher vagal indices (RMSSD r(18) = 0.288, p = 0.04), and with a baseline sympathovagal balance shifted toward parasympathetic predominance (LF/HF ratio r(18) = −0.289, p = 0.04). Associations of risk-taking behavior and resilience with cardiac autonomic modulation could be demonstrated, showing that HRV may be a valuable monitoring tool in this specific population; however further studies are warranted for validation.

High-Intensity Exercise Mitigates Cardiovascular Deconditioning During Long-Duration Bed Rest

Head-down-tilt bed rest (HDT) mimics the changes in hemodynamics and autonomic cardiovascular control induced by weightlessness. However, the time course and reciprocal interplay of these adaptations, and the effective exercise protocol as a countermeasure need further clarification. The overarching aim of this work (as part of a European Space Agency sponsored long-term bed rest study) was therefore to evaluate the time course of cardiovascular hemodynamics and autonomic control during prolonged HDT and to assess whether high-intensity, short-duration exercise could mitigate these effects. A total of n = 23 healthy, young, male participants were randomly allocated to two groups: training (TRAIN, n = 12) and non-training (CTRL, n = 11) before undergoing a 60-day HDT. The TRAIN group underwent a resistance training protocol using reactive jumps (5–6 times per week), whereas the CTRL group did not perform countermeasures. Finger blood pressure (BP), heart rate (HR), and stroke volume were collected beat-by-beat for 10 min in both sitting and supine positions 7 days before HDT (BDC−7) and 10 days after HDT (R+10), as well as on the 2nd (HDT2), 28th (HDT28), and 56th (HDT56) day of HDT. We investigated (1) the isolated effects of long-term HDT by comparing all the supine positions (including BDC−7 and R+10 at 0 degrees), and (2) the reactivity of the autonomic response before and after long-term HDT using a specific postural stimulus (i.e., supine vs. sitting). Two-factorial linear mixed models were used to assess the time course of HDT and the effect of the countermeasure. Starting from HDT28 onwards, HR increased (p < 0.02) and parasympathetic tone decreased exclusively in the CTRL group (p < 0.0001). Moreover, after 60-day HDT, CTRL participants showed significant impairments in increasing cardiac sympathovagal balance and controlling BP levels during postural shift (supine to sitting), whereas TRAIN participants did not. Results show that a 10-day recovery did not compensate for the cardiovascular and autonomic deconditioning following 60-day HDT. This has to be considered when designing rehabilitation programs—not only for astronauts but also in general public healthcare. High-intensity, short-duration exercise training effectively minimized these impairments and should therefore deserve consideration as a cardiovascular deconditioning countermeasure for spaceflight.

Limb Skin Temperature as a Tool to Predict Orthostatic Instability

Orthostatic instability is one of the main consequences of weightlessness or gravity challenge and plays as well a crucial role in public health, being one of the most frequent disease of aging. Therefore, the assessment of effective countermeasures, or even the possibility to predict, and thus prevent orthostatic instability is of great importance. Heat stress affects orthostatic stability and may lead to impaired consciousness and decrease in cerebral perfusion, specifically during the exposure to G-forces. Conversely, peripheral cooling can prevent orthostatic intolerance – even in normothermic healthy subjects. Indicators of peripheral vasodilation, as elevated skin surface temperatures, may mirror blood decentralization and an increased risk of orthostatic instability. Therefore, the aim of this study was to quantify orthostatic instability risk, by assessing in 20 fighter jet pilot candidates’ cutaneous limb temperatures, with respect to the occurrence of G-force-induced almost loss of consciousness (ALOC), before and during exposure to a push-pull maneuver, i.e., head-down tilt, combined with lower body negative pressure. Peripheral skin temperatures from the upper and lower (both proximal and distal) extremities and core body temperature via heat-flux approach (i.e., the Double Sensor), were continuously measured before and during the maneuver. The 55% of subjects that suffered an ALOC during the procedure had higher upper arm and thigh temperatures at baseline compared to the 45% that remained stable. No difference in baseline core body temperature and distal limbs (both upper and lower) skin temperatures were found between the two groups. Therefore, peripheral skin temperature data could be considered a predicting factor for ALOC, prior to rapid onset acceleration. Moreover, these findings could also find applications in patient care settings such as in intensive care units.

Gender-Specific Cardiovascular Reactions to +Gz Interval Training on a Short Arm Human Centrifuge

Cardiovascular deconditioning occurs in astronauts during microgravity exposure, and may lead to post-flight orthostatic intolerance, which is more prevalent in women than men. Intermittent artificial gravity is a potential countermeasure, which can effectively train the cardiovascular mechanisms responsible for maintaining orthostatic integrity. Since cardiovascular responses may differ between women and men during gravitational challenges, information regarding gender specific responses during intermittent artificial gravity exposure plays a crucial role in countermeasure strategies. This study implemented a +Gz interval training protocol using a ground based short arm human centrifuge, in order to assess its effectiveness in stimulating the components of orthostatic integrity, such as diastolic blood pressure, heart rate and vascular resistance amongst both genders. Twenty-eight participants (12 men/16 women) underwent a two-round graded +1/2/1 Gz profile, with each +Gz phase lasting 4 min. Cardiovascular parameters from each phase (averaged last 60 sec) were analyzed for significant changes with respect to baseline values. Twelve men and eleven women completed the session without interruption, while five women experienced an orthostatic event. These women had a significantly greater height and baseline mean arterial pressure than their counterparts. Throughout the +Gz interval session, women who completed the session exhibited significant increases in heart rate and systemic vascular resistance index throughout all +Gz phases, while exhibiting increases in diastolic blood pressure during several +Gz phases. Men expressed significant increases from baseline in diastolic blood pressure throughout the session with heart rate increases during the +2Gz phases, while no significant changes in vascular resistance were recorded. Furthermore, women exhibited non-significantly higher heart rates over men during all phases of +Gz. Based on these findings, this protocol proved to consistently stimulate the cardiovascular systems involved in orthostatic integrity to a larger extent amongst women than men. Thus the +Gz gradients used for this interval protocol may be beneficial for women as a countermeasure against microgravity induced cardiovascular deconditioning, whereas men may require higher +Gz gradients. Lastly, this study indicates that gender specific cardiovascular reactions are apparent during graded +Gz exposure while no significant differences regarding cardiovascular responses were found between women and men during intermittent artificial gravity training.

Cardiac Autonomic Modulations and Psychological Correlates in the Yukon Arctic Ultra: The Longest and the Coldest Ultramarathon

Studies on human physical performance in extreme environments have effectively approached the investigation of adaptation mechanisms and their physiological limits. As scientific interest in the interplay between physiological and psychological aspects of performance is growing, we aimed to investigate cardiac autonomic control, by means of heart rate variability, and psychological correlates, in competitors of a subarctic ultramarathon, taking place over a 690 km course (temperatures between +5 and -47°C). At baseline (PRE), after 277 km (D1), 383 km (D2), and post-race (POST, 690 km), heart rate (HR) recordings (supine, 15 min), psychometric measurements (Profile of Mood States/POMS, Borg fatigue, and Karolinska Sleepiness Scale scores both upon arrival and departure) were obtained in 16 competitors (12 men, 4 women, 38.6 ± 9.5 years). As not all participants reached the finish line, comparison of finishers (FIN, n = 10) and non-finishers (NON, n = 6), allowed differential assessment of performance. Resting HR increased overall significantly at D1 (FIN +15.9; NON +14.0 bpm), due to a significant decrease in parasympathetic drive. This decrease was in FIN only partially recovered toward POST. In FIN only, baseline HR was negatively correlated with mean velocity [r -0.63 (P.04)] and parasympathetic drive [pNN50+: r -0.67 (P.03)], a lower HR and a higher vagal tone predicting a better performance. Moreover, in FIN, a persistent increase of the long-term self-similarity coefficient, assessed by detrended fluctuation analysis (DFAα2), was retrieved, possibly due to higher alertness. As for psychometrics, at D1, POMS Vigor decreased (FIN: -7.0; NON: -3.8), while Fatigue augmented (FIN: +6.9; NON: +5.0). Sleepiness increased only in NON, while Borg scales did not exhibit changes. Baseline comparison of mood states with normative data for athletes displayed significantly higher positive mood in our athletes. Results show that: the race conditions induced early decreases in parasympathetic drive; the extent of vagal withdrawal, associated to the timing of its recovery, is crucial for success; pre-competition lower resting HR predicts a better performance; psychological profile is reliably depicted by POMS, but not by Borg fatigue scales. Therefore, assessment of heart rate variability and psychological profile may monitor and partly predict performance in long-duration ultramarathon in extreme cold environment.

Increased core body temperature in astronauts during long-duration space missions

Humans’ core body temperature (CBT) is strictly controlled within a narrow range. Various studies dealt with the impact of physical activity, clothing, and environmental factors on CBT regulation under terrestrial conditions. However, the effects of weightlessness on human thermoregulation are not well understood. Specifically, studies, investigating the effects of long-duration spaceflight on CBT at rest and during exercise are clearly lacking. We here show that during exercise CBT rises higher and faster in space than on Earth. Moreover, we observed for the first time a sustained increased astronauts’ CBT also under resting conditions. This increase of about 1 °C developed gradually over 2.5 months and was associated with augmented concentrations of interleukin-1 receptor antagonist, a key anti-inflammatory protein. Since even minor increases in CBT can impair physical and cognitive performance, both findings have a considerable impact on astronauts’ health and well-being during future long-term spaceflights. Moreover, our findings also pinpoint crucial physiological challenges for spacefaring civilizations, and raise questions about the assumption of a thermoregulatory set point in humans, and our evolutionary ability to adapt to climate changes on Earth.

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.

Relationship between anthropometric or functional characteristics and maximal serve velocity in professional tennis players

AIM

This study aims at investigating the possible relationships between anthropometric and functional parameters and maximal serve speed in professional tennis players.

METHODS

Eight professional male tennis players (age 23±4 [mean±SD] years; height 181±4 cm; body mass 80±4 kg; playing experience 14±4 years; weekly training practice 29±6 hours) were recruited. Anthropometric parameters (height, body mass, arm-racquet length, arm muscle area), jump performance (squat jump, counter movement jump; counter movement jump free), handgrip strength and first and second maximal serve speed were assessed.

RESULTS

Pearson's correlation coefficient showed significant (P<0.05) positive relationships between height and ball speed in both the first (r=0.78; P=0.02) and second (r=0.80; P=0.017) serve, and a significant negative correlation between serve speed and arm muscle area in first serve only (r=-0.78; P=0.03). In addition, a trend towards a positive correlation was observed between string tensions and serves speed for both first and second serves (r=0.54; P=0.16 and r=0.60; P=0.11, respectively). No significant relationship was found between serve speed and the other variables considered, including jumping performance parameters.

CONCLUSION

Height was confirmed to be the main anthropometric determinant of serves speed in professional tennis players.

Anthropometric and physiologic profiles of female professional yoga practitioners and energy expenditure during asanas execution

AIM

The present study aimed to: 1) define the anthropometric and physiological profiles of female professional yoga practitioner compared to that of other athletes; 2) evaluate the energy expenditure (EE) during a yoga session.

METHODS

The percentage fat mass (FM%) and fat free mass (FFM%), the maximal aerobic power (VO2max), the maximal voluntary contraction (MVC) of knee extensor muscles and the maximal anaerobic alactacid power (Wmax) were assessed in a group of yoga practitioners (Yo), long distance runners (LDR), sprinters (Spr), karate practitioners (Ka) and sedentary control subjects (Con). EE was evaluated in Yo during a yoga session (execution of a sequence of six yoga postures, called asanas).

RESULTS

FM% was significantly higher in Con (24.2±2.6%) than in other groups (18±1.9%, pooled data, P<0.05). FFM% did not differ among groups. VO2max was higher in LDR (55.6±1.8 mL min-1 kg-1) compared to other groups (41.7±3 mL min-1 kg-1, pooled data, P<0.05). MVC and Wmax were higher in Yo, Spr and Ka than in LDR and Con (P<0.05). In Yo, EE increased in comparison to baseline, during Sirasana execution only (+59%, P<0.05).

CONCLUSION

These data suggest that chronic yoga practice is associated with 1) values of FM%, FFM%, MVC and Wmax similar to those induced by sports requiring high degree of force and power of lower limb muscles, with maximal aerobic performance similar to control subjects; 2) low EE during most asanas execution.

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 coach's 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).

Cardiovascular adaptation to mudpack therapy in hypertensive subjects treated with different antihypertensive drugs

OBJECTIVE

In selected hypertensive subjects, cardiovascular adaptation to warm environments may be inadequate or even harmful: heating associated to mudpack therapy may cause unexpected hypotension. How different antihypertensive drugs may affect the cardiovascular response to mudpack therapy is poorly studied.

AIMS

To evaluate the effects of β-blockers and angiotensin II receptor antagonists/ACE inhibitors on the acute cardiovascular adaptation to mudpack treatment in SPA in elderly hypertensive patients.

PATIENTS AND METHODS

Thirty-one elderly subjects were divided in normotensive subjects (N; n=10) and hypertensive patients treated with ACE-inhibitors/Angiotensin II receptor antagonists (HTA; n=12) or with selective β1-blockers (HTB; n=9). Systolic (SBP) and diastolic (DBP) blood pressure were continuously recorded (10 min) in supine position, immediately before and during mudpack treatment (40°C). Heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were assessed.

RESULTS

During mudpack treatment SBP did not significantly change in both HTA and N groups (132±11 and 112±13 mmHg, respectively), but significantly decreased in HTB (111±18 mmHg, p < 0.01 vs baseline) patients. HR increased in all groups (HTA: 72±10 bpm; HTB: 65±6 bpm; N: 70±10 bpm; p < 0.01 vs baseline). A significant reduction (p < 0.01 vs baseline) in SV and CO occurred in HTB, but not in HTA and N groups. TPR significantly increased in HTB (1335±464 dyn.s.cm-5, p < 0.01 vs baseline) but not in HTA and N subjects (1389±385 dyn.s.cm-5 and 1245±323 dyn.s.cm-5, respectively).

CONCLUSIONS

Mud treatment did not cause relevant haemodynamic changes in normotensive and HTA-treated hypertensive subjects. Conversely, β-blocking treatment apparently limited the cardiovascular adaptation to thermic stress, through a possible reduction in myocardial contractility, thereby, causing a significant decrease, although not dangerous, in systolic blood pressure.

Polymorphisms of alpha-actinin-3 and ciliary neurotrophic factor in national-level Italian athletes

AIM

The R577X polymorphism of the alpha-actinin-3 (ACTN3) gene and the IVS1-6G>A polymorphism of the ciliary neurotrophic factor (CNTF) gene have been associated with a favourable muscle phenotype (more muscle fibres with high glycolytic activity), reduced predisposition for congenital dystrophy and resistance to sarcopenia in old age. The aim of this study was to look for evidence of selective pressure towards genotypes favourable for strong muscle activity in a sample of national-level Italian athletes.

METHODS

We analysed two stop codon polymorphisms in the DNA of 50 Italian athletes, specialised in power or endurance sports, and compared their genotypic distribution with those of a population of 50 controls. In a representative sub-group of athletes (N.=42) we then compared the genetic data with anaerobic threshold, assessed by an incremental exercise test up to exhaustion.

RESULTS

The athlete group showed an allelic distribution of ACTN3 (R/R:64%, R/X:16%, X/X:20%) and CNTF (G/G:72%, G/A:26%, A/A:2%), significantly imbalanced towards alleles R/R and G/G, respectively, compared to controls (ACTN3=R/R:40% R/X:22% X/X:38% and CNTF=G/G:52%, G/A:24%, A/A:24%) (p=0.0024 and p=0.0001, respectively). Only the ACTN3 577X/X polymorphism showed a significant association with the anaerobic threshold of athletes (F-ratio= 4.037; p=0.025). Factorial ANOVA demonstrated a non significant interaction between favourable allelic patterns of ACTN3 and CNTF genes on aerobic performance in the athlete group.

CONCLUSION

The relationship found between favourable muscle phenotype and this genetic profile may have interesting implications in sport performance and training, athlete selection and different clinical activities, such as physical rehabilitation and modifying phenotypes associated with neuromuscular diseases.

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

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.

Energy cost of spontaneous walking in Parkinson's disease patients

In healthy subjects, comfortable walking minimizes the energy cost (E (c)) of locomotion. In Parkinson's disease (PD) patients walking is slower than in healthy subjects: this may increase E (c). Our aims were to analyze gait and E (c) in PD patients during walking, particularly at self-selected speed, and the possible pathological, mechanical, and cardiorespiratory limitations. Fourteen mild-to-moderate PD and 14 control subjects were enrolled. Subjects underwent 5-min walking tests at two speeds: self-selected and as-fast-as-possible speeds. Cardiopulmonary and gait parameters (heart rate, ventilation, gas exchanges, step count) were recorded. Velocity was reduced in PD compared to control subjects at both speeds (P < 0.05), and PD patients had shorter strides (P < 0.05) at both speeds and reduced cadence (P = 0.01) at fastest speed. No significant difference was found in E (c) at self-selected (0.12 ± 0.04 versus 0.11 ± 0.02 mLO(2) kg(-1) m(-1) in PD and control subjects, respectively) and maximal (0.14 ± 0.03 versus 0.15 ± 0.02 mLO(2) kg(-1) m(-1) in PD and control subjects, respectively) speed. However, the E (c) increment from self-selected to fastest velocity was significantly lower (P = 0.02) in PD patients. PD patients failed to walk at a self-selected speed, which minimizes the E (c). This could be mainly due to the inability to develop a wider stride. Cardiorespiratory adaptation was not affected, except for the possible reduced cardiac adaptation observed in some (28%) cases. Presumably, rehabilitation procedures that improve flexibility and step length may help maintain walking ability.