Utilization of Wearable Technology in Individual Sports

Wearable technology can be utilized in injury prevention and training analysis. Different user groups have to be taken into account when designing wearable devices

An intelligent strategy for endurance training based on a virtual lactate sensor

Capítulo 5 confidencial a solicitud del autor. Tesis completa 210 p. --- Tesis censurada 196 p.In this thesis, a first fully operational virtual LT sensor was created for recreational runners. This way, a so demanded operational solution to help the training of recreational runners was created. Moreover, the Lactatus software was created to guide, ease the athletes' LT estimation process and implement the additional information obtained in this thesis into their training decision-making process. This way, the work of this thesis is made tangible, widely available and usable to recreational runners. This solution grew from the creation and formalization of a strategy to help pose and apply ML to complex phenomena, an important contribution of this thesis. This strategy combined an iterative meta-process and a satisficing approach to deal with the problem boundary discovery and reduce the problem complexity. Then, the design of the virtual LT sensor was divided into three steps: context characterization, content representation and next step decision. The formalization of this methodology and a modification of next step decision are novel contributions. Additionally, several novel techniques are used, including a standardization of the temporal axis, a modified stratified sampling and a computational algorithm to discover the inherent noise that the features may contain. This way, a robust strategy and methodology is created to design virtual sensors for problems with similar characteristics. The application of this methodology led to an important conclusion. Concretely, the Dmax LT intrinsic error analysis showed that a higher accuracy of the virtual LT sensor was unnecessary and even non-characterizable. This manifested the importance of understanding the variability of the output features with respect to the input errors. The computation algorithm also allows to LT protocols could also be evaluated from this perspective in order to quantitatively address their reliability. This may allow to make an objective cross-comparison of the accuracy of different LT protocols, something that, is not well addressed in the literature. One of the possible limitations of this solution is that the recreational runner population here characterized may not be representative of recreational runners of other culture, ethnicity or different contexts. However, one of the main advantages of providing a simple solution is that, unlike other black-box models, it is easily reproducible and adjustable, meaning that we have set a common ground for other researchers to evaluate the impact of our proposal. In the best-case scenario, future experiments done in other contexts will validate that we have been capable of discovering a common characteristic of recreational runner population. In the worst-case scenario, we have provided an easy to follow methodology and a strong prior that will allow to adjust the estimator according to individual characteristics of different populations

The proportional distribution of training at different intensities during different phases of the season by elite athletes participating in a variety of endurance sports

This review covers the scientific literature concerning the relative amounts of low-, moderate- and high-intensity training, quantified by different methods, performed by elite (Tier 4) and world-class (Tier 5) athletes participating in a variety of endurance sports during different phases of the season. Information was obtained through a non-systematic search of PubMed for relevant retrospective reports on the distribution of training (TID). The 34 articles retrieved yielded 175 TIDs, of which 120 involved quantifications on the basis of heart rate, time-in-zone or variations of the session goal approach, with demarcation of zones of exercise intensity utilizing physiological parameters. Next most common (n=37) was the use of velocity or power output as extrinsic parameters of quantification, followed by demarcation of zones on the basis of racing pace, i.e., velocity (n=14). Two studies employed ratings of perceived exertion to quantify TID. Of the TIDs identified, 85 (49%) involved single-case reports, of which 57 (67%) concerned cross-country skiing or the biathlon. Eighty-nine were pyramidal and 8 emphasized the threshold. Overall, 65 were polarized, of which 34 (52%) were derived from single-case reports on cross-country skiers or biathletes. With respect to training by elite and world-class athletes in all endurance disciplines, 91% (n=160) of the TIDs involved >60% low-intensity endurance exercise. Independent of the method of quantification, the relative amount of time spent in the different zones of exercise intensity varied widely between sports and different phases of the seaso

Developing Future Champions: Sport-Specific Motor Skill Performance in Youth Triathlon

This thesis aimed to explore the important motor skills for triathlon performance, create a measurement tool that could be used in the field, and measure the performance of an important motor skill over time to describe how changes in performance occur

Flexible Electrochemical Lactate Sensor

Lactic acid is a vital indicator for shock, trauma, stress, and exercise intolerance. It is a key biomarker for increases in stress levels and is the primary metabolically produced acid responsible for tissue acidosis that can lead to muscle fatigue and weakness. During intensive exercise, the muscles go through anerobic metabolism to produce energy. This leads to decreases in the blood flow of nutrients and oxygen to the muscles and increases in lactate production, which in turn cause lactic acidosis. Currently, changes in blood lactate concentrations are monitored by sensors that can be invasive via blood or wearable based sensors that use the enzyme lactate oxidase. Lactate oxidase produces hydrogen peroxide, which is a toxic byproduct and can foul the surface of the sensor. Here, we present the development of a noninvasive wearable electrochemical lactate biosensor for the detection of lactic acid. The bioelectrode was designed with buckypaper (BP), which is composed of a dense network of multi-walled carbon nanotubes. This material was chosen due to its low cost, high conductivity, flexibility, and high active surface area. D-Lactate dehydrogenase (D-LDH) was immobilized on the surface of the BP to facilitate the oxidation of lactic acid. The biosensor was then integrated into a polydimethylsiloxane (PDMS) flexible substrate platform. PDMS was chosen because of its lightweight, flexible, biocompatibility, and conformal properties. The sensor is designed to be placed on skin in order to measure the concentration of lactate in sweat. The concentration of lactate in sweat has been shown to be a good biomarker for evaluating the severity of peripheral occlusive arterial diseases and damage in soft tissue. The lactate biosensor developed in this work exhibited a dynamic linear range of 5 mM to 45 mM lactic acid with a good sensitivity of 1.388μA/mMcm2. It can measure higher than the average lactate concentration in sweat during exercise, which is 31mM. This electrochemical biosensor has the potential to be used for the real-time detection of lactic acid concentration in sweat, suggesting promising applications in clinical, biological and sports medicine fields

Study of the local oxygen saturation in cycling and differences between sexes

The development of non-invasive near-infrared spectroscopy (NIRS) technology has revolutionized the ability to perform muscle oxygenation measurements outside the laboratory context. In this regard, portable devices using this technology employ muscle oxygen saturation as a key variable to assess the availability of oxygen in muscles. Accordingly, the general aim of this thesis was to determine the reliability of portable NIRS technology in detecting muscle oxygenation thresholds and analyze the factors that may influence this detection, exploring muscle oxygenation profiles during an incremental cycling test. The main objective was divided into four specific aims: (1) To evaluate the reliability of determining the exercise intensity corresponding to the muscle oxygenation threshold; (2) To assess the effects of the symmetry and sex factors on the muscle oxygenation response; (3) To determine muscle oxygenation thresholds; and (4) To examine muscle oxygenation profiles. To address these objectives, a systematic review and an experimental study were conducted. The systematic review included 15 studies with a total of 344 participants, while the experimental study involved 26 cyclists and triathletes (15 males and 11 females). During the experimental study, muscle oxygen saturation was recorded using Moxy Monitor portable sensors on the vastus lateralis, tibialis anterior, gastrocnemius medialis on both sides, and the biceps femoris and triceps brachii of the preferred side. Measurements were performed during an incremental test and a constant-intensity test on a cycle ergometer. Additionally, other variables were recorded, such as blood lactate concentration, surface electromyography, skinfold thickness, and power output. The most relevant conclusions of this thesis document were that portable muscle oxygenation sensors demonstrated moderate to good reliability in determining the second threshold. The muscle oxygen saturation profiles of competitive cyclists and triathletes showed symmetrical responses on both preferred and non-preferred sides, although reductions were observed at certain intensities. Females, compared to males, exhibited lower muscle desaturation in all analyzed muscles, a difference that became more pronounced as metabolic demand increased. This suggests that males have a greater reliance on oxygen extraction at higher relative exercise intensities. The thesis showed that skinfold thickness affects muscle oxygen saturation measurements, emphasizing the importance of considering sex when interpreting these data. No SmO2 and cycling XXX mathematical method consistently determined the first muscle oxygenation threshold. However, the Exp-Dmax method showed good results in identifying the second muscle oxygenation threshold, with the vastus lateralis being the muscle with the best intraclass correlation coefficient. It is important to highlight that, although the second muscle oxygenation threshold can be determined during an incremental cycling test across different muscles, analyzing the muscle oxygen saturation profiles for each muscle can add value to the interpretation of results. Finally, the comparison of oxygenation and muscle activation signals revealed that power-generating and stabilizing muscles respond oppositely in muscle oxygen saturation and root mean square during the incremental cycling test. The increase in muscle activation reflects a rise in metabolic rate, requiring greater oxygen extraction to meet peripheral demands. This acute adaptation generates a moderate inverse concordance, depending on the muscle's role. However, the gastrocnemius medialis maintained stable activation without a significant decrease in muscle oxygen saturation

Modeling Energy Expenditure and Recovery in Cycling

The power-duration relationship, comprised of the parameters Critical power (CP) and work capacity (ϒ), has been used to model energy expenditure in cycling. For modeling recovery, the W\u27bal model has been used but lacks validation. Additionally, existing literature has not focused on quantifying or estimating the inherent trial-to-trial variability at the subject level, called the intra-individual variability (IIV), of CP and ϒ, posing challenges in modeling and optimization of performance. Thus, the objectives of this research are (i) to establish a method to quantify the IIV of CP and ϒ as determined from the 3-minute all-out test (3MT), (ii) to develop a testing protocol to understand expenditure and recovery of power and ϒ, (iii) to establish ϒ recovery profiles in terms of recovery power (Prec) and recovery duration (trec), and (iv) to present a case of cycling performance optimization using the energy management system based on athlete-specific models. Competitive amateur cyclists participated in two cycle ergometer studies: (i) repeatability of 3MTs to quantify IIV and (ii) intermittent cycling, in the laboratory to establish ϒ recovery profiles. The studies included an incremental ramp test to determine gas exchange threshold (GET), two or four 3MTs to determine CP and ϒ, and nine intermittent cycling tests to understand recovery of ϒ. From the repeated 3MT study, a new method was proposed to compare any two pairs of the 3MT at the individual level and estimate the IIVs associated with CP and ϒ. In the second study, a statistically significant two-way interaction effect between Prec and trec on ϒ recovery was observed followed by simple main effects seen only with respect to Prec at each trec. This indicates that Prec has a greater influence on the recovery of ϒ in a recovery interval lasting 2-15 minutes that follows a semi-exhaustive exertion interval above CP. The overestimation of the actual ϒ-balance at the end of the recovery interval by the W\u27bal models highlights the need for athlete-specific recovery parameters or models. Finally, the optimization tests conducted with one subject provide encouraging signs for the use of individualized recovery models in real-time in-situ performance optimization