Effects of trunk-focused exercise programs and how the training program and the individuals’

Trunk-focused exercise programs (TEP) refer to those training programs in which the main target of the exercises resides in the active and/or passive trunk/core structures. Although these programs have shown a positive impact in sport and health contexts throughout recent years, there are several limitations in the literature that hinder the understanding of TEP effect and their relationship to the individual and to the training load characteristics. In this sense, TEP are sometimes compared to exercise control groups and/or other exercise programs that include trunk-focused exercises. Furthermore, although the individual and the training program features are a basic aspect to optimize training programs, experimental TEP studies not always provide this information properly. To address these constraints, the present doctoral thesis includes two systematic reviews and an experimental study. The two systematic reviews aimed at an in-depth analysis of the literature on TEP both, to improve the knowledge about the trunk-focused exercise contribution to increase trunk physical fitness and ameliorate stroke and low back pain symptoms, and to better understand how the individuals and exercise programs characteristics modulate TEP effectiveness. Overall, although the quality of evidence was low, their results showed that TEP were effective to ameliorate stroke and patients’ non-specific chronic low back pain condition, with positive effects in all the outcomes analysed. Furthermore, the analysis of moderator factors revealed that TEP effectiveness in stroke patients seems to be higher when the initial trunk impairment is greater, the patients are older, and the intervention starts earlier. Importantly, the TEP impact on low back pain symptoms (mainly pain reduction) seems higher when a greater improvement in trunk and/or hip range of motion is recorded after the training program and participants have a lower body mass index. These results reinforce the importance of paying close attention to the individuals and to the exercise programs characteristics when designing this type of interventions. On the other hand, the experimental study overcomes some of the problems found in the systematic reviews, especially the lack of experimental works that objectively controlled the training load intensity. This study aimed at the comparison of the effects of a higher intensity and a higher volume core stability exercise (CSE) program on core stability, core endurance and whole-body dynamic balance in young physically active males, using a smartphone-accelerometer to control the CSE intensity. These study results showed the specificity of the effects caused by the CSE programs, with a larger increase in the lumbopelvic postural control during the execution of isometric CSE for the higher intensity CSE program and a larger core endurance increase for the higher volume CSE program. Interestingly, the performance of conventional isometric CSE in lying and quadruped positions during the CSE programs did not have a significant impact on the unstable sitting test, a sudden loading protocol and several whole-body dynamic balance tests. Altogether, the results of the studies included in this doctoral thesis highlight the importance of performing TEP to improve trunk performance, functional capacity,and health status in different populations. Specifically, the two systematic reviews showed how moderator factors related to both, the individual and the training program characteristics can play an important role in modulating TEP effectiveness, which should be considered to maximize and tailor the TEP benefits in stroke and low back pain patients. However, the quality of the evidence for all the outcomes analysed in these systematic reviews was low, and thus, higher quality studies are required to strengthen the evidence on the impact of performing trunk-focused exercises in stroke and low back pain rehabilitation programs. Regarding the experimental study, the training load control performed through the smartphone-accelerometer allowed to describe the specificity of the effects caused by a higher intensity and a higher volume CSE program in young physically active males. Further research is needed to characterize the dose-response relationship of CSE programs in different populations properly.Los programas de ejercicio focalizados en el tronco (PET) son aquellos programas de entrenamiento cuyo foco principal son las estructuras activas y/o pasivas del tronco/core. A pesar de que estos programas han mostrado un efecto positivo tanto en contextos deportivos como de salud a lo largo de los últimos años, se observan varias limitaciones en la literatura que dificultan entender adecuadamente el efecto que tienen estos programas y su relación tanto con las características de los participantes, como con las características de los programas de entrenamiento. En este sentido, los PET son comparados en ocasiones con grupos control y/u otros programas de entrenamiento que incluyen ejercicios focalizados en el tronco. Además, a pesar de que las características de los participantes y de los programas de entrenamiento son aspectos clave para su optimización, los estudios experimentales no siempre aportan esta información. Para abordar estas limitaciones, la presente tesis doctoral incluye dos revisiones sistemáticas y un estudio experimental. Las dos revisiones sistemáticas presentan un análisis detallado de la literatura relacionadas con los PET para, a) mejorar el conocimiento sobre la contribución de los ejercicios focalizados en el tronco sobre el desarrollo de la condición física del tronco y la mejora de los síntomas tanto en personas que han sufrido un ictus, como en pacientes con dolor lumbar, y b) comprender mejor cómo las características de los participantes y de los programas de entrenamiento modulan la efectividad de los PET. En general, a pesar de que la calidad de la evidencia fue baja, los resultados de estas revisiones mostraron la efectividad de los PET para mejorar la condición tanto de las personas que han sufrido un ictus, como de aquellas con dolor lumbar crónico inespecífico, obteniendo efectos positivos sobre todas las variables analizadas. Además, el análisis de los factores moderadores reveló que la efectividad de los PET en personas que han sufrido un ictus parece ser mayor cuando la afectación inicial del tronco es mayor, las personas son mayores o el programa de ejercicio comienza antes. Con respecto a las personas con dolor lumbar, el impacto de los PET sobre la reducción de los síntomas (especialmente la reducción del dolor), parece ser mayor cuando hay un mayor incremento del rango de movimiento del tronco y/o de la cadera y los participantes tienen un menor índice de masa corporal. Estos resultados refuerzan la importancia de prestar atención a las características de los participantes y de los programas de ejercicios cuando se diseñan este tipo de programas. Por otro lado, el estudio experimental que incluye esta tesis doctoral aborda algunos de los problemas observados en las revisiones sistemáticas, especialmente la falta de estudios experimentales que controlen de manera objetiva la carga de entrenamiento de los PET. En este sentido, este estudio tuvo como objetivo comparar los efectos de dos programas de ejercicios de estabilidad del tronco (EET), uno de mayor intensidad y otro de mayor volumen, sobre la estabilidad y resistencia del tronco y el equilibrio dinámico general en hombres jóvenes y físicamente activos, utilizando el acelerómetro integrado en un smartphone para controlar la intensidad de los EET. Los resultados mostraron la especificidad de los efectos de los programas de EET, con mayores mejoras sobre el control lumbo-pélvico durante la ejecución de EET isométricos en el grupo de mayor intensidad y un mayor efecto sobre la resistencia de los músculos tronco en el grupo de mayor volumen. Destacar también que la realización de EET isométricos en posiciones de tumbado y cuadrupedia no tuvo un impacto significativo sobre el test del asiento inestable, sobre un protocolo de perturbaciones súbitas y sobre varios test de equilibrio dinámico general. En resumen, los resultados de los estudios incluidos en esta Tesis Doctoral destacan la importancia de realizar PET para mejorar la condición física del tronco, la capacidad funcional y el estado de salud en diferentes poblaciones. Específicamente, las dos revisiones sistemáticas mostraron cómo factores moderadores relacionados con las características de los participantes y de los programas de entrenamiento pueden jugar un papel importante en la modulación de la efectividad de los PET, lo cual debería tenerse en cuenta para maximizar sus beneficios en personas que han sufrido un ictus y en pacientes con dolor lumbar. Sin embargo, la calidad de la evidencia de los estudios en los parámetros analizados fue baja y, por lo tanto, es necesario que estudios de mayor calidad refuercen y mejoren los resultados obtenidos sobre el impacto de los PET en estas poblaciones. Con respecto al estudio experimental, el control de la carga de entrenamiento a través del acelerómetro integrado en un smartphone permitió describir la especificidad de los efectos de un programa de EET de mayor intensidad y de otro de mayor volumen en hombres jóvenes y físicamente activos. Futuros estudios son necesarios para caracterizar de manera adecuada la relación dosis-respuesta de los programas de EET en diferentes poblaciones

Ejercicio físico y prevención del cáncer de colon

Proyecto desarrollado en castellano. Trata sobre los efectos de la actividad física en la prevención del cáncer de colon y cómo su práctica puede reducir el riesgo de padecerlo

IT NECESSARY TO NORMALIZE JUMP TEST RESULTS TO ANTHROPOMETRIC PARAMETERS?

The purpose of the present study was to analyse the relationship of different normalization methods in the jump performance, obtained from a digital application (My Jump 2 ®). 189 young women made up the sample. Each of them had to perform three attempts of a bilateral countermovement jump (CMJ) in front of a mobile device. The jump height (JH) and power (P) were the main results, which were processed to normalize them. The JH was normalized to height (JH/H) and to leg length (JH/LL). P was normalized to body mass (RP), while force values were divided by the time of jump to get the Explosive Index of Strength (EIS). The results showed a good association and poor prediction between the variables JH and P, not so between JH and EIS, where no significant relationship was observed. However, a strong relationship was observed between JH / LL and RP (r = 0.801; r2 = 0.641; p KEYWORDS: Smartphone app, vertical jump, biomechanics

Observational Screening Guidelines and Smartphone Accelerometer Thresholds to Establish the Intensity of Some of the Most Popular Core Stability Exercises

The lack of training load control, mainly exercise intensity, is one of the main limitations of core stability (CS) programs, which makes the training individualization and the analysis of the dose-response relationship difficult. The objectives of this study were to assess the inter-and intra-rater agreement when using new observational screening guidelines to decide if a core stability exercise represents an adequate training intensity level for a given participant. Besides, the relationship between experts' ratings based on these criteria and pelvic accelerations recorded with a smartphone accelerometer was also analyzed. Ten healthy physically active participants with a smartphone accelerometer placed on their pelvis were video-taped while performing a progression of seven variations of the front bridge, back bridge, side bridge and bird-dog exercises. Two expert and four non-expert raters watched the videos and used the observational screening guidelines to decide for each exercise variation if it represented an adequate training intensity level or not. In order to analyze the inter-and intra-rater agreement, several Kappa (κ) statistics were used. Receiver operating characteristic (ROC) curves to explore if the accelerometry allowed to establish pelvic acceleration thresholds representing the minimum level of exercise intensity for CS training. Cut-off acceleration values were calculated balancing sensitivity (Se) and 1-specifity (1-Sp) indexes (i.e., Youden index) or minimizing 1-Sp. The intra-and inter-rater analysis showed a substantial-high level of agreement with a prevalence-adjusted bias-adjusted Kappa > 0.69. The ROC curves showed that the acceleration thresholds for the bridging exercises were very similar, with global cut-off values of 0.35 m/s2 (Se = 82%; 1-Sp = 15%) when using the Youden Index and of 0.50 m/s2 when minimizing 1-Sp (Se = 31%), whilst the bird-dog exercise showed lower cut-off values (Youden Index: 0.21 m/s2, Se = 90%, 1-Sp = 16%; minimizing 1-Sp: 0.32 m/s2, Se = 40%). Overall, this study provides observational screening guidelines and smartphone accelerometer thresholds to facilitate the decision-making process when setting the intensity of some of the most popular core stability exercises in young physically active individual

Progressions of core stabilization exercises based on postural control challenge assessment

Purpose The intensity progression of core stabilization exercises (CSEs) is usually based on personal criteria rather than on objective parameters. To develop exercise progressions for four of the most common CSEs based on the postural control challenge imposed on the participants, and to analyze the effect of participants’ sex and postural control level on these progressions. Methods Seventy-six males and females performed five variations of front bridge, back bridge, side bridge and bird-dog exercises on two force platforms. The mean velocity of the center of pressure displacement was calculated to assess exercise intensity through the measurement of the participants’ body sway (PBS). Results In general, long bridges produced higher PBS than short bridges, bridging with single leg support produced higher PBS than bridging with double leg support and bridging on a hemisphere ball produced higher PBS than bridging on the floor. The most difficult bridging variations were those performed on a hemisphere ball with single leg support. Regarding the bird-dog, two-point positions produced higher PBS than three-point positions and the positions performed on a hemisphere ball produced higher PBS than those performed on the floor. Conclusion The CSE progressions obtained by males and females were very similar. However, the participants with high trunk control showed less significant differences between exercise variations than the participants with low trunk control, which shows the need to individualize the progressions according to the participants’ training level. Overall, this study provides useful information to guide the prescription of CSE progressions in young physically active individuals

Ejercicio físico y prevención del cáncer de colon

Proyecto desarrollado en castellano. Trata sobre los efectos de la actividad física en la prevención del cáncer de colon y cómo su práctica puede reducir el riesgo de padecerlo

Gender Differences in the Glycemic Response to Structured Exercise Interventions in Type II Diabetes Mellitus Adults: a Systematic Review

International Journal of Exercise Science 15(3): 948-961, 2022. Despite physiological sex differences in the prevalence, pathogenesis, and responses to pharmacologic therapies of glucose metabolism in type 2 diabetes mellitus (T2DM) and the current evidence regarding the benefits of physical activity in people with T2DM, there is still a lack of information about the response to physical activity in T2DM depending on the sex. Thus, the aim of the present systematic review was to analyze the physiological sex differences response to physical activity programs in adults with T2DM. A systematic review following PRISMA guidelines was performed up to 4th January 2022 in PubMed, SportDiscus and Web of Science databases. The research protocol of this systematic review was registered in PROSPERO (CRD42020189020). The PEDro scale and Cochrane risk of bias tools were used to analyze the quality and risk of bias of the studies included. Glycaemic (blood glucose, HbA1c, AUC glycemia, metabolic clearance rate, QUICKI) insulin (HOMA-IR, insulin levels, C-peptide) and cardiovascular parameters (VO2max, body fat mass, waist circumference, cardiovascular index) were registered. 6 studies met the inclusion criteria. Physical activity showed improvements in the glycaemic and insulin profiles and cardiovascular risk parameters for both men and women, but no relevant and significant differences between sex were found. No significant differences between males and females with regard to the effects elicited by physical activity on glycaemic biomarkers and cardiorespiratory fitness in individuals with T2DM were found. These results seem to lead towards the same physical activity prescription in men and women

Training intensity quantification of core stability exercises based on a smartphone accelerometer.

Although core stability (CS) training is largely used to enhance motor performance and prevent musculoskeletal injuries, the lack of methods to quantify CS training intensity hinders the design of CS programs and the comparison and generalization of their effects. The aim of this study was to analyze the reliability of accelerometers integrated into smartphones to quantify the intensity of several CS isometric exercises. Additionally, this study analyzed to what extent the pelvic acceleration data represent the local stability of the core structures or the whole-body postural control. Twenty-three male and female physically-active individuals performed two testing-sessions spaced one week apart, each consisting of two 6-second trials of five variations of frontal bridge, back bridge, lateral bridge and bird-dog exercises. In order to assess load intensity based on the postural control challenge of CS exercises, a smartphone accelerometer and two force platforms were used to measure the mean pelvic linear acceleration and the mean velocity of the centre of pressure displacement, respectively. Reliability was assessed through the intra-class correlation coefficient (ICC3,1) and the standard error of measurement (SEM). In addition, Pearson coefficient was used to analyze the correlation between parameters. The reliability analysis showed that most CS exercise variations obtained moderate-to-high reliability scores for pelvic acceleration (0.71<ICC<0.88; 13.23%≤SEM≤22.99%) and low-to-moderate reliability scores for centre of pressure displacement (0.24<ICC<0.89; 9.88%≤SEM≤35.90%). Regarding the correlation analysis, correlations between pelvic acceleration and centre of pressure displacement were moderate-to-high (0.52≤r≤0.81). Based on these results, smartphone accelerometers seem reliable devices to quantify isometric CS exercise intensity, which is useful to identify the individuals' CS status and to improve the dose-response characterization of CS programs

Is the Side Bridge Test Valid and Reliable for Assessing Trunk Lateral Flexor Endurance in Recreational Female Athletes?

The side bridge test (SBT) is one of the most popular tests to assess isometric trunk lateral flexor endurance. The aim of this study was to assess the validity and reliability of the SBT in healthy females. Twenty-four (24.58 ± 3.92 years) physically active (1–2 h of moderate physical activity, 2–3 times a week) females voluntarily participated in this study. The surface electromyography (EMG) of eight abdominal, back, shoulder and hip muscles was measured during the SBT. Normalized median frequency slopes (NMFslope) were calculated to analyze the muscle fatigue. The EMG amplitudes were normalized to maximum EMG values to assess muscle activity intensity. A one-week test-retest design was performed to evaluate the SBT reliability through the ICC3,1 and typical error. Higher NMFslopes and normalized EMG amplitudes were found in deltoids, abdominal obliques, rectus abdominis, and erector spinae in comparison to latissimus dorsi, gluteus medius, and rectus femoris. However, no significant differences were found between the trunk lateral flexors and the deltoids. Linear regression analysis showed that SBT performance could be significantly predicted by external oblique and deltoid NMFslope (adjusted R2 = 0.673) and by body mass and trunk height (adjusted R2 = 0.223). Consistency analysis showed a high intraclass correlation coefficient (0.81) and a relatively high typical error (10.95 s). Despite the good relative reliability of the SBT, its absolute reliability was low and its validity questionable, as the shoulder muscle activation and fatigue and the individuals’ anthropometric characteristics played an important role in SBT performance

Do Initial Trunk Impairment, Age, Intervention Onset, and Training Volume Modulate the Effectiveness of Additional Trunk Exercise Programs after Stroke? A Systematic Review with Meta-Analyses

The aim of this systematic review is to analyze how, after additional trunk-focused training programs (ATEP), motor recovery after a stroke is modulated by potential effect modifiers. Twenty randomized controlled studies that carried out ATEP were included. Results showed moderate-to-high effects in favor of ATEP for trunk function, balance ability, gait performance, and functional mobility. Studies with a higher initial trunk impairment obtained a higher effect on trunk function and balance; studies with older participants had a higher effect on trunk function, limit of stability, and functional mobility, but not on balance ability. Older and more affected patients were, as well, those who started the intervention earlier, which was also linked with higher effects on trunk function, balance, and gait performance. Longer ATEP found a high effect on trunk function and balance ability. The potential effect modifiers seem to be important in the modulation of the effectiveness of ATEP and should be considered in the design of rehabilitation programs. Thus, since potential effect modifiers seem to modulate ATEP effectiveness, future studies should consider them in their experimental designs to better understand their impact on stroke rehabilitation