Wearable biosensors are garnering substantial interest due to their potential to provide continuous, real-time physiological information via dynamic, noninvasive measurements of biochemical markers in biofluids, such as sweat, tears, saliva and interstitial fluid. Recent developments have focused on electrochemical and optical biosensors, together with advances in the noninvasive monitoring of biomarkers including metabolites, bacteria and hormones. A combination of multiplexed biosensing, microfluidic sampling and transport systems have been integrated, miniaturized and combined with flexible materials for improved wearability and ease of operation. Although wearable biosensors hold promise, a better understanding of the correlations between analyte concentrations in the blood and noninvasive biofluids is needed to improve reliability. An expanded set of on-body bioaffinity assays and more sensing strategies are needed to make more biomarkers accessible to monitoring. Large-cohort validation studies of wearable biosensor performance will be needed to underpin clinical acceptance. Accurate and reliable real-time sensing of physiological information using wearable biosensor technologies would have a broad impact on our daily lives.

Wearable biosensors for healthcare monitoring.

Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: current state of research.

http://web.mit.edu/ccrhq/hyneslab/2nd%20floor/2nd%20floor%20documents/Journal%20Club%20Exercise%20drugs.pdf

AMPK and PPARδ Agonists Are Exercise Mimetics

Many athletes, coaches, and support staff are taking an increasingly scientific approach to both designing and monitoring training programs. Appropriate load monitoring can aid in determining whether an athlete is adapting to a training program and in minimizing the risk of developing non-functional overreaching, illness, and/or injury. In order to gain an understanding of the training load and its effect on the athlete, a number of potential markers are available for use. However, very few of these markers have strong scientific evidence supporting their use, and there is yet to be a single, definitive marker described in the literature. Research has investigated a number of external load quantifying and monitoring tools, such as power output measuring devices, time-motion analysis, as well as internal load unit measures, including perception of effort, heart rate, blood lactate, and training impulse. Dissociation between external and internal load units may reveal the state of fatigue of an athlete. Other monitoring tools used by high-performance programs include heart rate recovery, neuromuscular function, biochemical/hormonal/immunological assessments, questionnaires and diaries, psychomotor speed, and sleep quality and quantity. The monitoring approach taken with athletes may depend on whether the athlete is engaging in individual or team sport activity; however, the importance of individualization of load monitoring cannot be over emphasized. Detecting meaningful changes with scientific and statistical approaches can provide confidence and certainty when implementing change. Appropriate monitoring of training load can provide important information to athletes and coaches; however, monitoring systems should be intuitive, provide efficient data analysis and interpretation, and enable efficient reporting of simple, yet scientifically valid, feedback.

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Monitoring Training Load to Understand Fatigue in Athletes

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Textbook Of Work Physiology Physiological Bases Of Exercise

Little attention has been directed toward identifying the changes which occur in salivary composition in response to exercise. To address this, our article first refers to the main aspects of salivary gland physiology. A knowledge of the neural control of salivary secretion is especially important for the understanding of the effects of exertion on salivary secretion. Both salivary output and composition depend on the activity of the autonomic nervous system and any modification of this activity can be observed indirectly by alterations in the salivary excretion. The effects of physical activity (with reference to factors such as exercise intensity and duration, or type of exercise protocol) on salivary composition are then considered. Exercise might indeed induce changes in several salivary components such as immunoglobulins, hormones, lactate, proteins and electrolytes. Saliva composition might therefore be used as an alternative noninvasive indicator of the response of the different body tissues and systems to physical exertion. In this respect, the response of salivary amylase and salivary electrolytes to incremental levels of exercise is of particular interest. Beyond a certain intensity of exercise, and coinciding with the accumulation of blood lactate (anaerobic threshold or AT), a ’saliva threshold’ (Tsa) does indeed exist. Tsa is the point during exercise at which the levels of salivary α-amylase and electrolytes (especially Na+) also begin to rise above baseline levels. The occurrence of the 2 thresholds (AT and Tsa) might, in turn, be attributable to the same underlying mechanism, that of increased adrenal sympathetic activity at high exercise intensities.

Saliva composition and exercise

LUCIA, A., J. HOYOS, M. PEREZ, and J. L. CHICHARRO. Heart rate and performance parameters in elite cyclists: a longitudinal study. Med. Sci. Sports Exerc., Vol. 32, No. 10, pp. 1777–1782, 2000.PurposeThis study was designed to evaluate the stability of target heart rate (HR) values corresponding to

Heart rate and performance parameters in elite cyclists: a longitudinal study.

Professional road cycling is an extreme endurance sport. Approximately 30 000 to 35 000km are cycled each year in training and competition and some races, such as the Tour de France last 21 days (∼100 hours of competition) during which professional cyclists (PC) must cover >3500km. In some phases of such a demanding sport, on the other hand, exercise intensity is surprisingly high, since PC must complete prolonged periods of exercise (i.e. time trials, high mountain ascents) at high percentages (∼90%) of maximal oxygen uptake (VO2max) [above the anaerobic threshold (AT)]. Although numerous studies have analysed the physiological responses of elite, amateur level road cyclists during the last 2 decades, their findings might not be directly extrapolated to professional cycling. Several studies have recently shown that PC exhibit some remarkable physiological responses and adaptations such as: an efficient respiratory system (i.e. lack of ‘tachypnoeic shift’ at high exercise intensities); a considerable reliance on fat metabolism even at high power outputs; or several neuromuscular adaptations (i.e. a great resistance to fatigue of slow motor units). This article extensively reviews the different responses and adaptations (cardiopulmonary system, metabolism, neuromuscular factors or endocrine system) to this sport. A special emphasis is placed on the evaluation of performance both in the laboratory (i.e. the controversial Conconi test, distinction between climbing and time trial ability, etc.) and during actual competitions such as the Tour de France.

Physiology of Professional Road Cycling

LUCIA, A., J. HOYOS, A. SANTALLA, C. EARNEST, and J. L. CHICHARRO. Tour de France versus Vuelta a Espana: Which Is Harder? Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 872- 878, 2003. Purpose: To compare the total exercise loads (intensity volume) of the Vuelta a Espana and Tour de France during the last year. Methods: Seven professional road cyclists (28 1 yr; V u O2max: 74.6 2.2 mL·kg 1 ·min 1 ) who participated in both Tour and Vuelta during the years 1997, 1999, 2000, or 2001 were collected as subjects. They wore a heart rate (HR) telemeter during each stage of the two races, and exercise intensity was divided into three phases according to the reference HR values obtained during a previous ramp cycle-ergometer test: phase I (ventilatory threshold (VT)), phase II (between VT and the respiratory compensation point (RCP)) and phase III (RCP). Total volume and intensity were integrated as a single variable. The score for volume intensity in each phase was computed by multiplying the accumulated duration in this phase by a multiplier for this particular phase. The total score for Tour and Vuelta was obtained by summating the results of the three phases. Results: The total loads (volume intensity) did not significantly differ between the two races ( P 0.05), despite a significantly longer total exercise time of the Tour (P 0.05) (5552 176 vs 5086 290 min). Conclusion: The physiological loads imposed on cyclists' bodies do not differ between the Tour and Vuelta, despite the longer duration of daily stages in the former race. Key Words: CYCLING, VOLUME, INTENSITY, HEART RATE, TELEMETER

Tour de France versus Vuelta a España: Which Is Harder?

The aim of the present investigation was to evaluate the heart rate response of 8 professional cyclists (26+/-3 yr; 68.9+/-5.2 kg; V02max: 74.0+/-5.8 ml x kg(-1) x min(-1)) during the 3-week Tour de France as an indicator of exercise intensity. Subjects wore a heart rate telemeter during 22 competition stages and recorded data were analysed using computer software. Two reference heart rates (corresponding to the first and second ventilatory thresholds or VT1 and VT2) were used to establish three levels of exercise intensity defined as phases I ( VT2) is substantially lower than that of light, aerobic exercise (<VT1), a clear distinction must be made between the different type of stages (i.e. easy, flat parcours vs mountain stages or time trials) and the role of each cyclist in the team must be also considered.

José L. Chicharro

Papers

Saliva composition and exercise

Heart rate and performance parameters in elite cyclists: a longitudinal study.

Physiology of Professional Road Cycling

Tour de France versus Vuelta a España: Which Is Harder?

Heart rate response to professional road cycling: the Tour de France.