The effect of changes in saddle height on coordination and its variability during pedalling cycle.

Modifications in saddle height affect the range of movement of the lower limb's joints during pedalling. Although its effect on movement patterns is poorly understood. The purpose of this study was to analyse the acute effects of small changes in bicycle saddle height on pedalling coordination and its variability. Lower extremity kinematic data were collected in random order for ten well-trained cyclists while pedalling at three different saddle heights: preferred, 2% higher and 2% lower than preferred position. A dynamical systems approach was used to quantify the coordination and its variability for selected joint couplings. Modifications in saddle height produced large changes in the frequency of movement patterns, although they were not enough to alter the coordination classification. Lowering the saddle height increased the frequency of the proximal coordinative hip-ankle pattern (F = 11.77, p < .01) and knee-ankle couplings (F = 14.39, p < .01), while decreasing inphase coordination (F > 11.03, p < .01) during the propulsive phase. Pedalling coordination variability was not affected, being greatest during the movement transitions and when the ankle joint was included in the coupling. This study demonstrated that pedalling pattern coordination and coordination variability were generally stable to acute small changes in saddle height in well-trained cyclists.

Krill-Oil-Dependent Increases in HS-Omega-3 Index, Plasma Choline and Antioxidant Capacity in Well-Conditioned Power Training Athletes.

There is evidence that both omega-3 polyunsaturated fatty acids (n-3 PUFAs) and choline can influence sports performance, but information establishing their combined effects when given in the form of krill oil during power training protocols is missing. The purpose of this study was therefore to characterize n-3 PUFA and choline profiles after a one-hour period of high-intensity physical workout after 12 weeks of supplementation. Thirty-five healthy power training athletes received either 2.5 g/day of Neptune krill oilTM (550 mg EPA/DHA and 150 mg choline) or olive oil (placebo) in a randomized double-blind design. After 12 weeks, only the krill oil group showed a significant HS-Omega-3 Index increase from 4.82 to 6.77% and a reduction in the ARA/EPA ratio (from 50.72 to 13.61%) (p < 0.001). The krill oil group showed significantly higher recovery of choline concentrations relative to the placebo group from the end of the first to the beginning of the second exercise test (p = 0.04) and an 8% decrease in total antioxidant capacity post-exercise versus 21% in the placebo group (p = 0.35). In conclusion, krill oil can be used as a nutritional strategy for increasing the HS-Omega-3 Index, recover choline concentrations and address oxidative stress after intense power trainings.

Jumping rope and whole-body vibration program effects on bone values in Olympic artistic swimmers.

INTRODUCTION: Artistic swimming seems not to benefit bone development like other out-of-water physical activities. To increase bone acquisition, artistic swimming should combine water training with weight-bearing impact or strength activities. Artistic swimmers can be a population at risk of developing osteopenia and osteoporosis in later life. The aim of the present study was to evaluate the effects of a training program on bone mineral density (BMD), bone mineral content (BMC) and body composition in an Olympic artistic swimming team. METHODS: Sixteen women aged 17-21 years, who train 30 h/week, at the Olympic Training Centre (Barcelona, Spain), were followed up over two seasons. The 1st season involved regular artistic swimming training without specific training to reduce the risk of osteopenia. The exercise intervention, jumping rope and whole-body vibration, was added in the 2nd season. The protocol included 20 min of training 2 days per week, over a 22-week period. Dual energy x-ray absorptiometry measured the bone variables and body composition. The daily diet, medical history and bone turnover markers were evaluated. RESULTS: The intervention program increased BMD on lumbar spine (2.10%, p = 0.002), total hip (2.07%, p = 0.001), and femoral neck (2.39%, p = 0.02). Lower limb's fat mass decreased (10.17%, p = 0.038). No significant differences were found for any of the measured anthropometric characteristics between both time points in the 1st season. In conclusions, combined jump rope and vibration should be considered to reduce the risk of bone damage in artistic swimmers.

Influence of Sex on Current Methods of Adjusting Saddle Height in Indoor Cycling.

ABSTRACT: Encarnación-Martínez, A, Ferrer-Roca, V, and García-López, J. Influence of sex on current methods of adjusting saddle height in indoor cycling. J Strength Cond Res 35(2): 519-526, 2021-The popularity of indoor cycling has increased in fitness centers, and therefore, proper bike fitting is important to avoid biomechanical-related injuries. However, no previous studies have compared the biomechanical kinematics of various existing protocols of saddle-height adjustment in indoor cycling. Furthermore, it was not clear if these protocols were appropriate for both men and women, as these equations were primarily obtained in male cyclists. Therefore, lower-limb joint kinematics were compared among 4 different protocols of saddle-height adjustment (1-Preferred, 2-Ferrer-Roca et al., 3-Lemond & Guimard, and 4-Static Goniometry) in 30 experienced indoor-cycling subjects (15 men and 15 women). Only 20-33% of the women had a knee extension while pedaling within the recommended range for each of the different protocols except for the preferred adjustment (73% were within). By contrast, all the protocols were moderately suitable for men (47-60% were within the recommended range). A multiple linear equation to estimate the recommended saddle height in both men and women (R2 = 0.917, p = 0.001) was obtained from the following variables: inseam length, stature, foot length, and knee angle. The differences in the findings between men and women may be partially explained by differences in anatomical structures, as well as the male-based equations, which argues the need for future investigations in female cyclists.

Muscle contributions to maximal single-leg forward braking and backward acceleration in elite athletes.

Abrupt deceleration is a common practice in several sports, where sudden changes of direction are needed to reach the highest performance level. When inappropriately performed, these actions can impose excessive mechanical loads at the lower limb joints, specifically at the knee and ankle joints, usually associated with increased risk of injury. This work aims to estimate muscle forces and muscle contributions to the acceleration of the center of mass during a rapid maximal single-leg forward braking and backward acceleration task. Fourteen elite male injury-free indoor-sports athletes participated in this work. Scaled generic musculoskeletal models, consisting of 12 segments, 23 degrees of freedom, and 92 muscle-tendon actuators were used in OpenSim software. Due to the nature of the musculoskeletal system, all muscles are considered when joint and segment positions, velocities, and accelerations are calculated, resulting in muscles acting to accelerate joints it does not span. The knowledge of muscle interaction during this multijoint task is important and was achieved through an induced acceleration analysis. The vasti (-9.18 ± 2.09 and -7.63 ± 1.33 N/Kg) were the main contributors to the centre of mass deceleration profile along the anterior/posterior direction, aided by the soleus muscle (9.72 ± 2.35 and 9.62 ± 2.07 N/Kg), which counteracted most of the effects applied by gravity along the vertical direction, during both phases. This study provides a computational approach to quantify the dynamical interactions between muscles and joints during an abrupt anterior/posterior deceleration task, thus giving robust and insightful indicators that can be implemented in injury prevention protocols.

Non-rigid alignment pipeline applied to human gait signals acquired with optical motion capture systems and inertial sensors.

An accurate gait characterization is fundamental for diagnosis and treatment in both clinical and sportive fields. Although several devices allow such measurements, the performance comparison between the acquired signals may be a challenging task. A novel pipeline for the accurate non-rigid alignment of gait signals is proposed. In this paper, the measurements of Inertial Measurement Units (IMU) and Optical Motion Capture Systems (OMCAP) are aligned using a modified version of the Dynamic Time Warping (DTW) algorithm. The differences between the two acquisitions are evaluated using both global (RMSE, Correlation Coefficient (CC)) and local (Statistical Parametric Mapping (SPM)) metrics. The method is applied to a data-set obtained measuring the gait of ten healthy subjects walking on a treadmill at three different gait paces. Results show a global bias between the signal acquisition of 0.05°. Regarding the global metrics, a mean RMSE value of 2.65° (0.73°) and an average CC value of 0.99 (0.01) were obtained. The SPM profile shows, in each gait cycle phase, the percentage of cases when two curves are statistically identical and reaches an average of 48% (22%).

Acute effects of small changes in crank length on gross efficiency and pedalling technique during submaximal cycling.

The main purpose of this study was to assess the acute effects of small changes in crank length (assumable by competitive cyclists) on metabolic cost and pedalling technique during submaximal cycling. Twelve amateur road cyclists performed three sets of submaximal pedalling (150, 200 and 250 W) at a constant cadence (91.3 ± 0.8 rpm) in a randomised order with three commonly used crank lengths, preferred (172.5-175 mm), +5 mm and -5 mm. Energy cost of pedalling, kinetic and kinematic variables were simultaneously registered. Changes in crank length had no significant effect on heart rate (144 ± 13, 145 ± 12 and 145 ± 13 bpm, respectively) and gross efficiency (GE) (20.4 ± 2.1, 20.1 ± 2.2 and 20.3 ± 2.4%, respectively). A longer crank induced a significant (P < 0.05) reduction of positive impulse proportion (PIP) (0.9-1.9%) due to a greater maximum (1.0-2.3 N · m) and minimum torque (1.0-2.2 N · m). At the same time, the maximum flexion and range of motion of the hip and knee joints were significantly increased (1.8-3.4° and P < 0.05), whereas the ankle joint was not affected. In conclusion, the biomechanical changes due to a longer crank did not alter the metabolic cost of pedalling, although they could have long-term adverse effects. Therefore, in case of doubt between two lengths, the shorter one might be recommended.

Evaluación de factores de riesgo de lesión del ligamento cruzado anterior en jugadores de fútbol de alto nivel / Evaluation of risk factors for anterior cruciate ligament injury in high-level male football players

El objetivo del presente estudio es la detección de factores de riesgo de lesión de ligamento cruzado anterior (LCA) en jugadores de fútbol profesionales al comienzo de la pretemporada. Treinta y cinco jugadores de fútbol de alto nivel fueron analizados mediante un sistema de análisis del movimiento y 2 plataformas de fuerzas. Se analizó el ángulo de rodilla en el plano frontal (valgo-varo) y las fuerzas verticales de reacción de ambas extremidades durante la fase de aterrizaje del drop jump. Se determinó el coeficiente de correlación intraclase. La significación estadística fue considerada para p < 0,05. Se encontraron diferencias significativas entre la extremidad más fuerte y la débil en el impulso excéntrico (32,4 Ns; IC 95%, 22,9-41,8 Ns; p < 0,05) y en el impulso concéntrico (14,4 Ns; IC 95%, 9,8-19,1 Ns; p < 0,05). El 31,4% de los futbolistas presentaron valores de falta de balance entre extremidades superior al 15%, y el 14,2% de los jugadores aterrizaron con un ángulo de rodillas en el plano frontal mayor a 20°. La metodología propuesta en el presente estudio ha demostrado ser fiable y sensible en la detección de factores de riesgo asociados a la lesión del LCA

Anterior cruciate ligament (ACL) injury is one of the most serious time-loss injuries in football. The purpose of the present study is to evaluate risk factors of ACL injuries in high-level football players during the preseason. Thirty-five high-level players were captured by a video movement analysis system and a two-force platform. Frontal plane knee angle and vertical force were measured during the landing phase of the drop jump. Intraclass correlation coefficient was determined to assess test-retest reliability, and α level of 0.05 was considered statistically significant. There were significant differences between the stronger and weaker leg in eccentric (32.4 Ns; 95% CI; 22.9-41.8 Ns; P < 0.05) and concentric impulse (14.4 Ns; 95% CI, 9,8-19,1 Ns; P <0.05). Additionally, 31.4% of the subjects obtained a lower limb strength imbalance higher than 15%. Furthermore, 14.2% of the subjects obtained a frontal plane knee valgus angle higher than 20°. Findings of the present study are particularly significant as a functional deficit higher than 15% and an increased in valgus motion at the knee suggests an altered muscular control of the lower extremity. Furthermore, results confirmed that the test proposed in this study is reliable and sensitive to identify ACL injury intrinsic risk factors in high level male football players in order to introduce the necessary preventive measures

Acute effects of small changes in bicycle saddle height on gross efficiency and lower limb kinematics.

The aim of the present study was to assess the acute effects of small changes in bicycle saddle height on gross efficiency (GE) and lower-limb kinematics. Well-trained cyclists (n = 14) performed a submaximal pedaling test (~70-75% of the v[Combining Dot Above]O2max) at constant cadence (90 rpm). It consisted of 3 randomized sets of 6 minutes with the preferred saddle height, 2% higher and 2% lower. Gross efficiency was significantly lower and oxygen consumption (v[Combining Dot Above]O2) was significantly higher when raising the saddle (GE = 19.9 ± 1.5%; V[Combining Dot Above]O2max = 43.8 ml·kg·min) than when lowering it (GE = 20.4 ± 1.3%; V[Combining Dot Above]O2 = 42.8 ml·kg·min). Additionally, a change of 0.8% in GE (20.6 ± 1.6% to 19.8 ± 1.6%, p < 0.05) was observed when comparing the positions where the best and worst GE was obtained. A significant effect of the small changes in saddle height on lower limb kinematics was also observed (p < 0.05). The differences between lower and higher saddle positions, in hip, knee, and ankle joints were an increase of extension (~4, 7, and 8°, respectively), a decrease of flexion (~3, 4, and 4°, respectively) and, consequently, an increase of the range of movement (~1, 3, and 4°, respectively). The results of the present study indicate that small changes in saddle height affected GE and lower limb kinematics The observed changes in lower limb kinematics could justify, in part, the GE changes. Further research should evaluate long-term effects of these small modifications in the seat height on GE and lower limb kinematics.

Sodium nitrate supplementation does not enhance performance of endurance athletes.

PURPOSE: Supplementation with inorganic nitrate has been suggested to be an ergogenic aid for athletes as nitric oxide donor. The purpose of this study was to determine whether ingestion of inorganic sodium nitrate benefits well-trained athletes performing a 40-min exercise test in laboratory conditions. In addition, we investigated the effect of this supplement on plasma levels of endothelin-1 (ET-1) and in nitrated proteins. METHODS: Thirteen trained athletes participated in this randomized, double-blind, crossover study. They performed a 40-min cycle ergometer distance-trial test after two 3-d periods of dietary supplementation with sodium nitrate (10 mg·kg of body mass) or placebo. RESULTS: Concentration of plasma nitrate (256 ± 35 µM) and nitrite (334 ± 86 nM) increased significantly (P < 0.05) after nitrate supplementation compared with placebo (nitrate: 44 ± 11 µM; nitrite: 187 ± 43 nM). In terms of exercise performance, there were no differences in either the mean distance (nitrate: 26.4 ± 1.1 km; placebo: 26.3 ± 1.2 km; P = 0.61) or mean power output (nitrate: 258 ± 28 W; placebo: 257 ± 28 W; P = 0.89) between treatments. Plasma ET-1 increased significantly (P < 0.05) just after exercise in nitrate (4.0 ± 0.8 pg·mL) and placebo (2.4 ± 0.4 pg·mL) conditions. This increase was significantly greater (P < 0.05) in the nitrate group. Levels of nitrated proteins did not differ between treatments (nitrate: preexercise, 91% ± 23%; postexercise, 81% ± 23%; placebo: preexercise, 95% ± 20%; postexercise, 99% ± 19%). CONCLUSION: Sodium nitrate supplementation did not improve a 40-min distance-trial performance in endurance athletes. In addition, concentration of plasma ET-1 increased significantly after exercise after supplementation with sodium nitrate.

Influence of saddle height on lower limb kinematics in well-trained cyclists: static vs. dynamic evaluation in bike fitting.

In cycling, proper saddle height is important because it contributes to the mechanical work of the lower limb joints, thus altering pedaling efficiency. The appropriate method to select optimal saddle height is still unknown. This study was conducted to compare a static (anthropometric measurements) vs. a dynamic method (2D analysis) to adjust saddle height. Therefore, an examination of the relationship between saddle height, anthropometrics, pedaling angles, and hamstring flexibility was carried out. Saddle height outside of the recommended range (106-109% of inseam length) was observed in 56.5% of the subjects. Inappropriate knee flexion angles using the dynamic method were observed in 26% of subjects. The results of this study support the concept that adjusting saddle height to 106-109% of inseam length may not ensure an optimal knee flexion (30-40°). To solve these discrepancies, we applied a multiple linear regression to study the relationship between anthropometrics, pedaling angles, and saddle height. The results support the contention that saddle height, inseam length, and knee angle are highly related (R = 0.963, p < 0.001). We propose a novel equation that relates these factors to recommend an optimal saddle height (108.6-110.4% of inseam length).