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

Unraveling the Effects of Expertise and Fatigue on Kinematics and Stride-to-Stride Variability in Running

Unser Körper ermöglicht es uns, ohne große Anstrengung komplexe Bewegungen auszuführen. Aufgrund der Vielzahl von Freiheitsgraden (DoF) im Muskel-Skelett-System ist unser Körper ein hochredundantes System. Für jede denkbare Bewegung gibt es daher mehrere Lösungsmöglichkeiten, welche wiederum zu einer Vielzahl an Bewegungsausführungen führen. Von außen betrachtet liegt die Vermutung nahe, dass innerhalb einer zyklischen Bewegung, wie z.B. dem Laufen, immer wieder der gleiche Bewegungsablauf ausgeführt wird. Dies führt oft zu der Annahme, dass die Beobachtung eines einzigen Laufzyklus ausreicht, um die Biomechanik des Laufens zu analysieren. Dabei werden allerdings Informationen übersehen, die in den Variationen zwischen aufeinanderfolgenden Zyklen liegen. Tatsächlich könnte eine reine Reproduktion desselben Laufzyklus unter gleichen Bedingungen zu Verletzungen führen, da immer dieselben Strukturen in demselben Maße belastet werden würden. Jedoch ist der Zustand des Läufers und seiner Randbedingungen von Laufzyklus zu Laufzyklus nicht immer identisch, daher ist eine exakte Reproduktion desselben Bewegungsmusters unwahrscheinlich. Eine mögliche Veränderung der Randbedingungen könnte das Auftreten von Ermüdung sein, welche bei Ausdauersportarten unvermeidlich ist. Die Vielzahl gleichwertiger Bewegungslösungen und die daraus resultierende Variabilität zwischen einzelnen Laufzyklen eines Läufers sind daher wertvolle Merkmale und ein wichtiges Thema für Forschungsarbeiten im Kontext der menschlichen Bewegungskoordination. Auf dem Forschungsgebiet der Bewegungsvariabilität wurden zwei vielversprechende spezifische Methoden entwickelt und auf biomechanische Daten angewendet: die Uncontrolled Manifold-Methode (UCM) und die Tolerance Noise Covariation-Methode (TNC). Die UCM hat ihren Ursprung im Forschungsfeld der motorischen Kontrolle, wohingegen die TNC aus dem Bereich des motorischen Lernens kommt. Mit Hilfe der UCM und der TNC Methoden wird analysiert, wie die Variabilität auf der Ebene der Gelenkwinkel mit der Variabilität der Zielgröße zusammenhängt. Sie wurden hauptsächlich auf eingeschränkte Bewegungen mit nur wenigen DoF angewendet und kaum zur Untersuchung von Ganzkörperbewegungen, wie z.B. des Laufens, genutzt. Bei Untersuchungen des Gehens wurde festgestellt, dass trotz Zyklus-zu-Zyklus Variabilität (SSV) auf unterschiedlichen Ebenen (z.B. Gelenkwinkel) diese so kanalisiert werden kann, dass eine Zielgröße (z.B. Körperschwerpunk, CoM) über die Zyklen hinweg annähernd konstant bleibt. Diese Arbeit erörtert auf der Basis von fünf Studien, wie sich Expertise und Ermüdung auf die Laufkinematik auswirken, indem sie nicht nur eine biomechanische Analyse der Effekte von Ermüdung auf die Lauf-Kinematik durchführt, sondern auch komplexe Methoden zur Analyse der Bewegungsvariabilität anwendet. Da diese Methoden in der internationalen sportwissenschaftlichen Forschung bisher kaum Anwendung gefunden haben, wird mit der vorliegenden Arbeit auch geprüft, ob sich die anhand von einfachen, experimentellen Paradigmen der Grundlagenforschung entwickelten Methoden, gewinnbringend auf sportwissenschaftliche Problemstellungen übertragen lassen. In der ersten Studie wurden die Auswirkungen von Expertise auf die SSV des CoM beim Laufen bei 10 und 15 km/h analysiert. Novizen zeigten bei 15 km/h eine größere Variabilität als Experten. In der zweiten Studie wurde ein klassischer biomechanischer Ansatz gewählt, um die Ermüdungsreaktionen von erfahrenen Läufern zu untersuchen. Dabei wurden Veränderungen sowohl in Raum-Zeit- und Steifigkeitsparametern, als auch in der Gelenkkinematik gefunden. Diese Ergebnisse zeigten, dass die Kinematik im ermüdeten Zustand deutlich verändert ist. Die dritte Studie erweiterte diese Erkenntnisse durch die Verwendung der UCM-Methode. Dabei wurde ein probandenspezifisches 3D-Modell für den menschlichen Körper eingeführt, um den Ganzkörper-CoM genau berechnen zu können. Es wurden geringe Veränderungen bei Ermüdung gefunden. Dies zeigte, dass erfahrene Läufer in der Lage sind, ihre CoM-Trajektorie auch in einem ermüdeten Zustand zu kontrollieren. In der vierten Studie wurden diese Ergebnisse durch die Verwendung der TNC-Methode erweitert. Es zeigte sich, dass die Variabilität des CoM sowohl in medio-lateraler als auch in vertikaler Richtung mit Ermüdung zunimmt. In der fünften Studie wurde wieder ein klassischer biomechanischer Ansatz gewählt, um die Reaktionen auf Ermüdung zu charakterisieren, dieses Mal bei Lauf-Novizen. Es wurden keine Veränderungen in den Raum-Zeit- und Steifigkeitsparametern gefunden, obwohl die Gelenkkinematik durch die Ermüdung beeinflusst wurde. Diese Ergebnisse deuten darauf hin, dass Novizen möglicherweise Strategien fehlen, um eine konstante Laufgeschwindigkeit unter Ermüdung beizubehalten. Mit dieser Studienreihe wird das Wissen über die Auswirkungen von Expertise und Ermüdung auf die Kinematik und SSV beim Laufen erweitert. Nachdem die grundsätzliche Anwendbarkeit von neuen Ansätzen, wie der UCM oder der TNC Methode, auf komplexe sportwissenschaftliche Probleme gezeigt wurde, können diese Methoden bei der Anwendung auf praxisorientierte Probleme in der Sportwissenschaft geprüft und zu verbessert werden

The Effect of Periodized Strength Training and Periodized Concurrent Training on Running Performance

The objective of this dissertation was to evaluate the changes in preparedness over the course of training for a marathon in two well-trained runners. The athletes completed periodized strength training or a periodized concurrent training. This dissertation consisted of two separate investigations: Study 1 – The purpose of this study was to monitor changes in force production ability and running performance in one sub-elite marathon runner before, during, and after undertaking a short-term block periodized strength training program. The athlete ceased strength training during the off-seasons and resumed testing after 10. The athlete experienced likely true, meaningful changes in force production characteristics during the taper after the training program. Improvements in force production characteristics coincided with improvements in running economy. Both force production characteristics and running economy reversed after the withdraw from strength training. However, both measures remained improved from initial baseline. The improvement in running economy and force production likely coincided with a cardiovascular de-training period, due to a reduction in aerobic training during the off-season. Therefore, strength training may have independent effects on running economy and running performance. These results indicate that endurance runners may better optimize performance by improving force production characteristics via periodized strength training program, and should avoid prolonged periods without strength training. Study 2 – The purpose of this study was to monitor the concurrent and divergent changes in athlete preparedness and performance over a competitive training cycle in two marathon athletes. One athlete added a block periodized strength training program to a non-periodized endurance training program (NBP Athlete). The other athlete (BP Athlete) completed an integrated, concurrent block periodized program using HIT over-reach endurance training. Both athlete displayed improvements in running performance and running economy over the duration of the monitoring program. The BP Athlete displayed earlier and greater magnitudes of performance improvements. These results indicate that strength training can enhance running economy in marathon athletes, performance may be better optimized through periodized integration of strength and endurance training, and the use of HIT over-reach blocks may improve marathon relevant fitness characteristic within the ecologically valid context of an athlete’s training cycle

Bioenergetics, Training and Performance in Distance Running

There has always been great interest from the scientific community on identifying training strategies to improve performance in long distance races. Most of the studies have focused on elite athletes, although amateur runners represent the majority of participants in endurance events. The need to study strategies for amateur athletes stems from their limited technical skills and the lack of time available for training compared to elite athletes. The purpose of the first study was to evaluate the effect of flywheel strength training and high intensity training protocols on RE and strength parameters in a group of recreational runners. Twenty-nine recreational runners were recruited to take part in the study and were randomly assigned to flywheel strength training (FST; n = 9; 44.5\ub16.0yrs; V\u2019O2max 48.8\ub15.2 ml min-1 kg-1), high intensity training (HIT; n = 9; 42.2\ub18.6yrs; V\u2019O2max 50.3\ub13.7ml min-1 kg-1) or low intensity training (LIT; n = 11; 45.4\ub18.0yrs; V\u2019O2max 50.2\ub16.8ml min-1 kg-1) groups. Before and after 8 weeks of an experimental period, maximal oxygen uptake (V\u2019O2max), ventilatory thresholds (VT), maximal dynamic force (1RM) and anthropometric data were evaluated. The FST group showed significant increases (p < 0.05) in 1RM and RE. No differences were found in the other groups. Anthropometric data were unchanged after the training period. The results of this study indicate that in recreational runners, flywheel strength training seems able to obtain improvements in RE and neuromuscular adaptation. In the second study, the aim was to compare the effects of different training distribution on changes in limiting factors and performance. The main difference between training model is the distribution of time spent in different HR zone, 77/3/20 % and 40/50/10 % of total training time for Polarized Endurance Training (PET) and Focused Endurance Training (FET). Training program included four training sessions per week for PET and 3 for FET. Thirty-eight recreational runners were recruited to take part in the study. They were randomly assigned to PET (n = 19; 43.2\ub18.4yrs; V\u2019O2max 52.9\ub18.1 ml min-1 kg-1) and FET (n=19; 39.4\ub18.5yrs; V\u2019O2max 53.4\ub18.3 ml min-1 kg-1) for an 8-week period. The training plans was designed to reach a similar score for both total TRIMP accumulated over 8 weeks (2492 \ub1 72.1 TRIMPs) and mean TRIMP accumulated each week (311 \ub1 9). Before and after training periods all the subjects performed laboratory incremental test to exhaustion to individualized V\u2019O2max, ventilatory threshold and intensity hr zone based on it, field performance test on 2km and 21km and muscle function tests 1RM, Squat jump (SJ) and Counter Movement Jump (CMJ). The total training time in 8 weeks was 29.8 \ub1 3.07 hours and 24.8 \ub1 1.96 for PET and FET group respectively, and no significant differences was found between groups in any investigated variable. Significant improvement from pre-to post training were observed in speed at V\u2019O2max (vV\u2019O2max), speed at VT2, speed at VT1 and RE for both groups. The results of this study are not able to define which approach is preferable with recreational runners in terms of intensity distribution. The strategies evaluated in this thesis show that the "recreational runners" model is able to provide data that meet research need and to respond to the training with adaptations similar to those recorded for elite athletes. Moreover, these strategies wants to represent for coaches and athlete alternative practices to the common training methods and ideas for future studies

Physiological responses to various durations and intensities of warmup

Warmup has been a general practice for most athletes to engage in prior to a practice or competitive race. However, there has been little scientific evidence, specifically for the endurance athlete concerning the appropriate duration, intensity, or a combination of duration and intensity needed to enhance performance. Therefore, the purpose of this study was to determine how different combinations of durations and intensities of warmup affect heart rate (HR), lactic acid· (LA), minute ventilation (VE), respiratory exchange ratio (R) and rating of perceived exertion (RPE) during a 5 minute treadmill run at 80% VO2 max. Subjects included four male and four female trained (male mean VO2 max= 55.3; female mean vo2 max= 48.6) endurance athletes (mean age= 30.6 yr, SD=+ 4.4). Subjects randomly participated in one of the warmup conditions, followed by a 5 minute run at 80% vo2 max. The four warmup conditions were low intensity, short duration (LISD), low intensity, long duration (LILD), high intensity, short duration (HISD) and high intensity, long duration (HILD}. The low and high intensities were set at 40% vo2 max and 80% VO2 max, and the short and long durations were set at 5 and 20 minutes, respectively. Results of the 2 x 2 ANOVA showed significant (p\u3c.01) main effects for duration for RPE, with 20 minutes significantly higher than 5 minutes, and intensity for HR (p\u3c.01), with 70% VO2 max significantly greater than 40% vo2 max. There was no significance found for LA, Rand VE. The omega squared analysis showed that for RPE and HR 68.7% and 39.6% of the variance among the conditions was due to the duration and intensity of the warrnup, respectively. In summary, no particular warrnup produced optimal effects on all of the physiological factors associated with performance. Therefore, it is recommended that warrnup within the range of 40% to 70% V02 max for 5 or 20 minutes produced equivalent effects for most of the physiological variables studied

Physiological responses to various durations and intensities of warmup

The purpose of this study was to determine how different combinations of durations and intensities of warmup affect heart rate (HR), blood lactate levels (LA), minute venilation (VE), respiratory exchange ratio and ratings of perceived exertion (RPE) during a treadmill edurance run at 80% VO2 max

Muscle activation patterns in shoulder impingement patients

Introduction: Shoulder impingement is one of the most common presentations of shoulder joint problems 1. It appears to be caused by a reduction in the sub-acromial space as the humerus abducts between 60o -120o – the 'painful arc'. Structures between the humeral head and the acromion are thus pinched causing pain and further pathology 2. Shoulder muscle activity can influence this joint space but it is unclear whether this is a cause or effect in impingement patients. This study aimed to observe muscle activation patterns in normal and impingement shoulder patients and determine if there were any significant differences. Method: 19 adult subjects were asked to perform shoulder abduction in their symptomatic arm and non-symptomatic. 10 of these subjects (age 47.9 ± 11.2) were screened for shoulder impingement, and 9 subjects (age 38.9 ± 14.3) had no history of shoulder pathology. Surface EMG was used to collect data for 6 shoulder muscles (Upper, middle and lower trapezius, serratus anterior, infraspinatus, middle deltoids) which was then filtered and fully rectified. Subjects performed 3 smooth unilateral abduction movements at a cadence of 16 beats of a metronome set at 60bpm, and the mean of their results was recorded. T-tests were used to indicate any statistical significance in the data sets. Significance was set at P<0.05. Results: There was a significant difference in muscle activation with serratus anterior in particular showing a very low level of activation throughout the range when compared to normal shoulder activation patterns (<30%). Middle deltoid recruitment was significantly reduced between 60-90o in the impingement group (30:58%).Trends were noted in other muscles with upper trapezius and infraspinatus activating more rapidly and erratically (63:25%; 60:27% respectively), and lower trapezius with less recruitment (13:30%) in the patient group, although these did not quite reach significance. Conclusion: There appears to be some interesting alterations in muscle recruitment patterns in impingement shoulder patients when compared against their own unaffected shoulders and the control group. In particular changes in scapula control (serratus anterior and trapezius) and lateral rotation (infraspinatus), which have direct influence on the sub-acromial space, should be noted. It is still not clear whether these alterations are causative or reactionary, but this finding gives a clear indication to the importance of addressing muscle reeducation as part of a rehabilitation programme in shoulder impingement patients

Relationship between maturation, strength, movement competency and motor skill performance in adolescent males

Despite the limited research available, understanding how maturation, strength and movement skill influence long-term athletic development is crucial when working with young people. Therefore, the purpose of this study was to examine the relationships between maturation, strength, movement competency and motor skill performance in young males. One-hundred and ten adolescent males (mean ± SD; age 13.8 ± 0.6 y; height = 165.8 ± 9.4 cm; mass = 57.1 ± 13.9 kg; maturity offset = 0.1 ± 0.9 y) were tested for movement competency (resistance training skills battery, RTSB), strength (isometric midthigh pull, IMTP), speed (10, 20, 30 m sprint), power (horizontal jump, HJ; vertical jump, CMJ; seated medicine ball throw, SMBT) and repeat sprint ability (RSA). Results showed that maturity offset had small correlations with CMJ (r = 0.25), moderate correlations with speed (r = -0.31 to -0.35) and HJ (r = 0.33), and strong correlations with absolute strength (r = 0.70) and SMBT (r = 0.76). Relative strength showed small to large correlations with all motor skill variables (r = 0.27-0.61), whereas absolute strength was significantly correlated with speed, power and RSA (r = 0.29-0.83). The RTSB score showed small to moderate correlations with RSA (r = 0.27) and 20 and 30 m sprint performance (r = -0.34). Relative strength was the strongest predictor for all sprints (adjusted R2 = 0.38-0.40), CMJ (adjusted R2 = 0.16) and RSA (adjusted R2 = 0.27), whereas absolute strength was strongest for HJ and SMBT (adjusted R2 = 0.21 and 0.70, respectively). Maturity offset further explained sprint, CMJ and SMBT performance whereas RTSB did not help predict the performance of any dependent variables. Strength, movement competency and maturity are important considerations for motor skill performance, but strength may be most important and should be developed early on using appropriate training recommendations