Leg Power Research Articles

Lower and Upper Body Muscle Characteristics among Collegiate Baseball and Soccer Players

Increased muscular strength in athletes has shown a prolific effect in the development of sports skills including jumping, throwing, sprinting, and change of direction abilities. Sports, such as soccer and baseball, differ largely in specific characteristics needed for success. To date, few studies have reported differences in sports specific skills between these two sports to measure and quantify the neuromechanical capacity. PURPOSE: To compare both lower and upper body strength among collegiate baseball (BB) and soccer (SC) players. METHODS: In this non-randomized cross-sectional study, 19 baseball and 19 soccer players, age ranges from 18-25 years completed the protocols. Lower body strength and power were assessed by a two-leg press maximal strength test (1RM) and vertical jump test (Just Jump Mat, Tendo Sports Machine), respectively. Upper body strength was assessed by a handgrip (HG) test using handgrip dynamometry (Takei, Japan). RESULTS: Independent sample t-test showed BB players (88.05 ± 7.1 kg) were significantly heavier than SC players (72.1 ± 7.2 kg) (p<0.05). However, weight-adjusted upper body strength and leg power were not significantly different between the two groups. BB players had significantly higher jump height (JH), time in air, and 1RM leg strength compared to SC players (p<0.05). CONCLUSIONS: BB players showed significantly higher lower muscle strength compared to SC players, however no differences were observed for peak power. These results provide a quantitative measure of the performance difference between these two sports, reinforcing the need for further research along with large sample size to assess the possible differences in training effectiveness and inherent characteristics between BB and SC players.Table 1: Athlete Performance Variables (Adjusted Mean ± SE)

Sex Differences in Muscle-Bone Interactions in Chinese Men and Women

Muscle-bone interactions are important for bone health as mechanical forces from muscular contraction place large stresses on bone. Little is known about sex differences in bone and muscle characteristics in Asians. PURPOSE: To examine sex differences in bone characteristics, grip strength, and lower body strength and power in Chinese adults (n=53). METHODS: Chinese males (n=28) and females (n=25) had body composition and aBMD (total body, lumbar spine, dual femur) assessed by DXA, and bone geometry (4%, 38%, 66%) of the non-dominant tibia measured by pQCT. Leg strength (two-leg press) and power (jump mat) and maximal grip strength (handgrip dynamometer) were measured. RESULTS: There were no sex differences in physical activity or calcium intake. After adjusting for height and weight, males had significantly greater leg press 1RM, grip strength, jump height, jump time, lumbar spine aBMD, 4% total BMC, 4% total area, and 4% bone strength index (BSI) (p<0.05) than females. In males, leg 1RM was positively correlated with total body aBMD (r= 0.427), and left femoral neck aBMD (r=0.445), and jump power was positively correlated with total body aBMD (r=0.580) and all hip aBMD variables (r=.487 to 0.646) (all p< 0.05). Females generally had stronger correlations between muscle and bone variables: leg 1RM (all p<0.05) and jump power (all p<0.003) were positively related to all aBMD variables (r=0.432 to 0.819). Jump power and BSI were positively correlated (r=0.378, p=0.048) in males, whereas jump power and leg 1RM showed moderate to strong correlations with 4% total BMC, total area, and total BSI (r=0.460 to 0.836, p<0.05) in females. CONCLUSION: Based on our findings, Chinese males had greater bone size, bone strength, and muscle strength than females; however, females exhibited more and stronger relationships between muscle and bone variables than males.Table 1: Sex Differences in Muscle and Bone variables (unadjusted Means ± SD)

Comparison of Functional Tests of Leg Power in Collegiate Athletes

Comparison of Functional Tests of Leg Power in Collegiate Athletes

Physiological and Motor Performance Parameters of Female Athlete and Non-Athlete Students in a Ghana University: A Comparative Pilot Study

Background: Obesity is a common health concern, especially in females. Although prominent effects of the participation in sports on females’ physiological and motor outcomes have been widely investigated, comparative evidence among female athlete and non-athlete students in a Ghana University is needed. Objectives: This pilot study compared the physiological and motor performance parameters of female athlete and non-athlete students in a Ghana University. Methods: Thirty-one female students aged 17 to 26 years (21.18 ± 1.79) assigned to the two groups (athletes and non-athletes) participated in this cross-sectional study. The athletes participated in university sports for three years, while non-athletes were monitored for the same period. The evaluated parameters consisted of blood pressure, heart rate, body mass index (BMI), %body fat, muscle mass, visceral fat, VO2max, muscle endurance, arms’ and shoulders’ power, the power of legs, agility, and speed. Results: Athletes significantly had better VO2max (P = 0.004), the power of arms and shoulders (P = 0.005) and speed (P = 0.014) compared with non-athletes. Differences in heart rate, blood pressure (systolic and diastolic), BMI, %body fat, muscle mass, visceral fat, the power of legs, and agility were not significant (P > 0.05). Conclusions: There was no significant difference between female athletes and non-athletes in physiological and motor performance attributes. It suggests that the participation of these female students in sports did not affect healthy physiological and motor performance outcomes. Training of university female athletes should emphasize health outcomes, while motor performance attributes are prioritized.

Superior Effects of Modified Chen-Style Tai Chi versus 24-Style Tai Chi on Cognitive Function, Fitness, and Balance Performance in Adults over 55.

Background: Cognitive decline and balance impairment are prevalent in the aging population. Previous studies investigated the beneficial effects of 24-style Tai Chi (TC-24) on either cognitive function or balance performance of older adults. It still remains largely unknown whether modified Chen-style TC (MTC) that includes 18 complex movements is more beneficial for these age-related health outcomes, as compared to TC-24. Objective: We investigated if MTC would show greater effects than TC-24 on global cognitive function and balance-related outcomes among older adults. Methods: We conducted a randomized trial where 80 eligible adults aged over 55 were allocated into two different styles of Tai Chi (TC) arms (sixty-minute session × three times per week, 12 weeks). Outcome assessments were performed at three time periods (baseline, Week 6, and Week 12) and included the Chinese Version of the Montreal Cognitive Assessment (MoCA) for overall cognitive function, One-leg Standing Test (LST) for static balance, Timed Up and Go Test (TUGT) for dynamic balance, chair Stand Test (CST) for leg power, and the six-meter Walk Test (6MWT) for aerobic exercise capacity. Results: Compared to TC-24 arm, MTC arm demonstrated significantly greater improvements in MoCA, LST, TUGT, CST, and 6MWT (all p < 0.05). Conclusions: Both forms of TC were effective in enhancing global cognitive function, balance, and fitness. Furthermore, MTC was more effective than TC-24 in enhancing these health-related parameters in an aging population.

The Association between Body Mass Index and Physical Fitness among Adolescents

The lifestyle and diet of today's modern society can lead to overweight and obesity. Overweight and obesity is now beginning to worry. This study aims to provide a description of the condition of Body Mass Index (BMI) and physical fitness among adolescents in Bangka Belitung Islands in 2017, and how BMI and physical fitness are associated. 105 adolescents were participants of this study, 90 male and 15 female adolescents. Participants aged ± 18 years in the year of the study conducted. Anthropometry is performed to identify participants' BMI. Performance tests were conducted to identify the components of physical fitness related to the health of the participants. Performance of vertical jump (leg power), sprint 60 meter (speed), push-up (strength and endurance of arm muscle), sit-up (strength and endurance of abdominal muscles), and run / walk distance 1000/1200 meters (cardiorespiratory endurance). BMI has a significant correlation with the strength and endurance of arm muscle (t = 3.79, p &lt; 0.05). BMI has a significant correlation with leg power (t = 4.97, p &lt; 0.01). BMI correlates significantly with speed (t = 4.04, p &lt; 0.05). CRE is only significantly correlated with abdominal muscle strength and endurance (t= 2.51, p &lt; 0.01). Overweight and obesity can be prevented through the provision of a program of physical activity that meets the rules of physical fitness. The program should be provided from primary to senior high school and it’s a sustainable long-term program at every level of education at school. Hopefully overweight and obesity can be prevented.

DIFERENCIAS MOTORAS EN ATLETAS CADETES DE TAEKWONDO SEGÚN NIVEL COMPETITIVO

The aim of this study was to determine the differences between Taekwondo cadet athletes belonging to different competition levels in terms of anthropometry, legs power, flexibility and reaction time. Twenty male athletes were analysed, divided in two groups: national medallist and non-national medallist. Data of every athlete’s anthropometric measurements, reaction speed ability, leg power and hip ROM (range of movement) were taken. Medallist athletes showed significantly lower values for height, arm span, foot reaction time (dominant and non-dominant) and non-dominant hand reaction time; and higher values for leg length, passive hip flexion, active hip abduction and passive hip abduction in ROM tests. Slight differences observed between medallists and non-medallists in leg power (CMJ), body fat (Σ skinfolds) and active hip flexion do not agree with previous studies. Knowing this information could be interesting for coaches in order to carry out talent detection programs.

The Effects of Tai Chi on Markers of Atherosclerosis, Lower-limb Physical Function, and Cognitive Ability in Adults Aged Over 60: A Randomized Controlled Trial.

Objective: The purpose of this study was to investigate the effects of Tai Chi (TC) on arterial stiffness, physical function of lower-limb, and cognitive ability in adults aged over 60. Methods: This study was a prospective and randomized 12-week intervention trial with three repeated measurements (baseline, 6, and 12 weeks). Sixty healthy adults who met the inclusion criteria were randomly allocated into three training conditions (TC-24, TC-42, and TC-56) matched by gender, with 20 participants (10 males, 10 females) in each of the three groups. We measured the following health outcomes, including markers of atherosclerosis, physical function (leg power, and static and dynamic balance) of lower-limb, and cognitive ability. Results: When all three TC groups (p < 0.05) have showed significant improvements on these outcomes but overall cognitive ability at 6 or 12 weeks training period, TC-56 appears to have superior effects on arterial stiffness and static/dynamic balance in the present study. Conclusions: Study results of the present study add to growing body of evidence regarding therapeutic TC for health promotion and disease prevention in aging population. Future studies should further determine whether TC-42 and TC-56 are beneficial for other non-Chinese populations, with rigorous research design and follow-up assessment.

Effects of Combined Training on Physical Fitness and Anthropometric Measures among Boys Aged 8 to 12 Years in the Physical Education Setting

Some studies have shown that resistance training combined with plyometric training is more time-efficient and effective for fitness development. The degree and frequency of combined training might influence the benefit of training to maintain time. To better understand this phenomenon of the degree and frequency of combined training in pre- and early pubertal boys, we have provided a more specific recommendation for physical education teachers thus that they are able to prescribe an exercise plan for their students in the physical education setting. We aimed to investigate the effects of combined training followed by 12 weeks of a reduced/detraining period on physical fitness and anthropometric features in 8 to 12-year old boys. Forty-six healthy boys were randomly assigned to either an experimental group (EG, n = 31) or a control group (CG, n = 15). Besides regular physical education classes (PE), participants in the EG performed a combined training program (resistance and plyometric training) twice weekly for 12 weeks. In the CG, participants only underwent PE classes twice per week. Then, the trained boys were randomly assigned to either a reduced training group (RTG, n = 14) or a training cessation group (TCG, n = 17). The RTG continued a reduced combined training program once a week with PE for additional 12 weeks. In the TCG, participants only kept their PE classes twice a week for 12 weeks. We assessed physical fitness performances (biceps curl, leg power, and running speed) and anthropometric features at baseline, after 12 weeks of combined training, and after 12 weeks of reduced training/detraining. We observed a significantly greater decrease in biceps girth in the EG (p = 0.049, d = 0.636), as compared to the CG. With regard to the physical fitness measures after the 12-week combined training, the EG showed significantly greater increase on biceps curl (p = 0.005, d = 0.92) and standing long jump (p = 0.015, d = 0.8) in comparison with the CG, whereas a significantly greater improvement on 30 m sprint speed (p = 0.031, d = 0.707) was observed in the EG, as compared to the CG. With regard to detraining and reduced training, results indicated a significantly greater increase on this outcome in the RTG (p = 0.038, d = 0.938), as compared to the TCG. Resistance training combined with plyometric training can be a safe and effective way to enhance the selected aspects of physical fitness, as well as reduce muscular girth in boys aged between 8 and 12 years. The frequency of one session per week in the combined training seems to provide an additional benefit to prevent leg power of lower limb from rapid deterioration.

Mechanical energetics and dynamics of uphill double-poling on roller-skis at different incline-speed combinations.

ObjectivesThe purpose of this study was to investigate the effect of different incline-speed combinations, at equal external power outputs, on the mechanics and energetics of the double-poling (DP) technique in cross-country skiing.MethodsFourteen elite male cross-country skiers performed treadmill DP on roller-skis at low, moderate, and high mean external power outputs (Pmean) up a shallow incline (5%, INC5), at which DP is preferred, and up a steep incline (12%, INC12), at which DP is not preferred. Speed was set to produce equal Pmean at both inclines. From recorded kinematics and dynamics, arm power (Parm) and trunk+leg power (PT+L) were derived, as were pole propulsion power (Ppole) and body mechanical energy perpendicular to the treadmill surface (Ebody⊥).ResultsOver a locomotion cycle, the arms contributed 63% to Pmean at INC5 but surprisingly only 54% at INC12 (P<0.001), with no effect of Pmean (P = 0.312). Thus, the trunk and legs contributed substantially to Pmean both at INC5 (37%) and INC12 (46%). At both inclines, PT+L generation during the swing phase increased approximately linearly with Pmean, which increased Ebody⊥. Within the poling phase, ~30–35% of the body energy which was developed during the preceding swing phase was transferred into propulsive pole power on both inclines. At INC5, the amount of negative PT+L during the poling phase was larger than at INC12, and this difference increased with Pmean.ConclusionsThe considerable larger amount of negative PT+L during poling at INC5 than at INC12 indicate that the legs and trunk generate more power than ‘necessary’ during the swing phase and thus must absorb more energy during the poling phase. This larger surplus of PT+L at INC5 seems necessary for positioning the body and poles so that high Parm generation can occur in a short time. At INC12, less Parm is generated, probably due to less advantageous working conditions for the arms, related to body and pole positioning. These incline differences seem linked to shorter swing and longer poling times during steep uphill DP, which are due to the increased influence of gravity and slower speed at steep inclines.

An Analysis over Physical and Physiological Parameters of Elementary School Children Taking Part in A Sport Climbing Exercise

This study is intended to analyze any improvement in flexibility, balance, strength (hand, grip, arm, torso, leg) and physiological (body weight, body mass index, body fat percentage) parameters for elementary school children with no background of sport climbing in a sport climbing training they attend. The physical and physiological parameters of the subjects were measured at the outset of the study and at the end of month two. Height (H), body weight (W), body mass index (BMI), body fat percentage (BFP), Flamingo Balance Test (FBT) for balance, Sit and Reach Test (SRT) for flexibility, Standing Broad Jump (SBJ) for explosive leg power, Sit-Ups Test (SUT) to be performed in 30 seconds for abdominal strength, Bent Arm Hang (BAH) test for endurance, hand grip strength (HGS) test for grip, and 10 x 5 meter shuttle run (SR) tests for sprint speed were conducted as a part of preliminary and posttests. The subjects took part in a 90-minute sport climbing exercise on a daily basis. The results of the preliminary and posttests pointed to a significant difference of p<.001 in body weight, body mass index, balance, flexibility, torso strength, arm strength, grip strength and sprint speed, and of p<.005 in body fat percentage. There was no significant difference between preliminary and post test results of the students who did not take part in any sport climbing exercise. In conclusion, physical and physiological parameters of students who take up sport climbing as early as in an elementary school do improve.

HUBUNGAN ANTARA POWER TUNGKAI, KOORDINASI MATA-TANGAN, DAN RASA PERCAYA DIRI DENGAN HASIL KEMAMPUAN LAY-UP SHOOT BOLA BASKET

AbstactThe purpose of this study, to find out how much the relationship between power limbs, eye-hand coordination, and a sense of confidence with the results of the ability to shoot shoots on basketball.This research method uses a correlation method with product moment calculation techniques. The sample amounted to 20 people from all extra-basketball players / athletes in SMK Negeri 4 Kota Pontianak.The calculation results obtained show; 1). There is a positive relationship between Leg Power (X1) with the results of Lay-up Shoot (Y) skills of 68%. 2). There is a positive relationship between hand eye coordination (X2), with the results of Lay-up Shoot skills (Y ) of 42.2%. 3) There is a positive relationship between self-confidence (X3) and the results of Lay-up Shoot (Y) skills of 47.5%.Thus there is a positive relationship between power limbs (X1) eye-hand coordination (X2) and self-confidence (X3) together towards the results of the Lay-up Shoot skill (Y) obtained from the R correlation coefficient of 81.8% . So the conclusions from this study show that power limbs, eye-hand coordination, and self-confidence have a significant relationship with the results of basketball shoot lay-up capabilities.Keywords: Lay-up, Leg Power, Hand Eye Coordination, Confidence

ASSOCIATION OF FITNESS, BODY CIRCUMFERENCE, MUSCLE MASS, AND EXERCISE HABITS WITH METABOLIC SYNDROME

Background and objectiveMetabolic syndrome (MetS) can be improved by diet, cessation of smoking, and in particular exercise. The purpose of this study was to analyze the association of exercise-related factors such as fitness, exercise habits, muscle, and body fat with MetS. MethodsData were collected for research purposes from 398 males aged 40–50 years. Appendicular skeletal muscle mass (ASM) and body fat percentage were analyzed using bioelectrical impedance analysis (BIA). Fitness was evaluated using cardiopulmonary fitness, grip strength, and leg power. Exercise habits included exercise frequency, intensity, and duration. Data were analyzed using the odds ratio (OR), calculated by logistic regression analysis. ResultsThere was no significant difference in age between the non-MetS (51.1 years) and the MetS (51.5 years) groups. Differences in dyslipidemia and fitness variables classified as MetS risk factors were significant between groups. The group with the highest cardiopulmonary fitness had an OR of 0.426 (95% confidence interval [CI], 0.191–0.948) when compared with the lowest group, while grip strength was not significantly different. Obesity factors such as body fat percentage, body mass index, and waist circumference were significantly prevalent. The group with the largest thigh circumference had an OR of 0.299 (95% CI, 0.101–0.881) when compared to the group with the smallest thigh circumference. Calf circumference did not yield significant results. The group with the highest ASM had an OR of 0.346 when compared with the lowest group. Higher exercise frequency and longer duration were associated with a lower prevalence of MetS. ConclusionAmong physical strength, circumference, muscle mass, and obesity factors, MetS was most affected by obesity factors. Furthermore, higher cardiopulmonary fitness and frequent exercise can be helpful for MetS prevention.

Power Decoupling Control for Capacitance Reduction in Cascaded-H-Bridge-Converter-Based Regenerative Motor Drive Systems

A cascaded H-bridge (CHB) converter-based medium or high-voltage motor drive system, that consists of three single-phase CHB chains, may suffer a severe second-harmonic ripple power issue. Oversizing dc capacitors and using active power decoupling control with additional active or passive components are the two possible ways to address this issue, but this is achieved at the expense of increased system cost and complexity. This paper proposes a power decoupling control to tackle this issue without using any extra components for regenerative CHB-based converters. By introducing a set of negative-sequence decoupling currents to the front-end pulsewidth-modulated rectifier of each submodule, the second-harmonic ripple power can be removed from the submodule dc capacitors, and all the ripple power in the transformer core legs can be counteracted without affecting the magnetic flux and the grid current. The decoupling current is derived from the input and output measurements of the CHB converter. It gives the minimal increase of the modulation index and has no impacts on the input and output power quality. The effectiveness of the proposed control is verified in simulations and a 72-kW experimental prototype.

The association between the level of physical activity with spinal posture and physical fitness parameters in early adolescence

Background/Aim. A low level of physical activity and sedentary lifestyle affects the body posture in adolescents. The aim of this study was to assess the core relation between the level of physical activity and spinal posture as well as physical fitness parameters in 11?14 years old teenagers. Methods. The cross-sectional study included 532 children, aged from 11 to 14 years. The study was carried out at three Lithuanian schools in 2011?2013. The Youth Physical Activity Questionnaire (YPAQ) was used to assess physical activity. Spinal posture was assessed according to the Hoeger visual posture assessment method. Physical capacity was evaluated using a 6-min walking test (6 MWT) and by calculating maximum oxygen consumption (VO2max). Other physical fitness such as the general balance, flexibility, explosive leg power and abdominal muscle endurance were evaluated by applying the European Fitness Test (Eurofit). According to time spent doing moderate to vigorous intensity physical activities (MVPA), the sample was divided into 2 groups ? a low activity level group and moderate to vigorous intensity physical activity level group. We compared the spinal posture evaluation results and physical fitness parameters between groups as well as correlations between the duration of MVPA, spinal posture evaluation results and physical fitness parameters. Results. The study showed that 22.2% of teenagers had a low physical activity level and 16% of teenagers had an incorrect posture. The teenagers of low physical activity group were less physically fit and had the poorer posture than teenagers in the MVPA group. During the 6MWT, the teenagers in the low physical activity group walked on average 63.2 m less (p = 0.002), and their VO2max was 0.8 mL/kg/min lower (p = 0.006) than that of teenagers in the MVPA group. The teenagers in the low physical activity group also did not perform as well in the explosive leg power and abdominal muscle endurance tests compared to teenagers in the MVPA group. Correlations between the duration of MVPA and spinal posture evaluation results as well as some physical fitness parameters were very weak. Conclusion. The teenagers of low physical activity were less physically capable and had poorer posture than the teenagers in the MVPA group.

Effects of an Eight-Week Superimposed Submaximal Dynamic Whole-Body Electromyostimulation Training on Strength and Power Parameters of the Leg Muscles: A Randomized Controlled Intervention Study.

The purpose of this study was to assess the effects of dynamic superimposed submaximal whole-body electromyostimulation (WB-EMS) training on maximal strength and power parameters of the leg muscles compared with a similar dynamic training without WB-EMS. Eighteen male sport students were randomly assigned either to a WB-EMS intervention (INT; n = 9; age: 28.8 (SD: 3.0) years; body mass: 80.2 (6.6) kg; strength training experience: 4.6 (2.8) years) or a traditional strength training group (CON; n = 9; age: 22.8 (2.5) years; body mass: 77.6 (9.0) kg; strength training experience: 4.5 (2.9) years). Both training intervention programs were performed twice a week over a period of 8 weeks with the only difference that INT performed all dynamic exercises (e.g., split squats, glute-ham raises, jumps, and tappings) with superimposed WB-EMS. WB-EMS intensity was adjusted to 70% of the individual maximal tolerable pain to ensure dynamic movement. Before (PRE), after (POST) and 2 weeks after the intervention (FU), performance indices were assessed by maximal strength (Fmax) and maximal power (Pmax) testing on the leg extension (LE), leg curl (LC), and leg press (LP) machine as primary endpoints. Additionally, vertical and horizontal jumps and 30 m sprint tests were conducted as secondary endpoints at PRE, POST and FU testing. Significant time effects were observed for strength and power parameters on LE and LC (LE Fmax +5.0%; LC Pmax +13.5%). A significant time × group interaction effect was merely observed for Fmax on the LE where follow-up post hoc testing showed significantly higher improvements in the INT group from PRE to POST and PRE to FU (INT: +7.7%, p < 0.01; CON: +2.1%). These findings indicate that the combination of dynamic exercises and superimposed submaximal WB-EMS seems to be effective in order to improve leg strength and power. However, in young healthy adults the effects of superimposed WB-EMS were similar to the effects of dynamic resistance training without EMS, with the only exception of a significantly greater increase in leg extension Fmax in the WB-EMS group.

The Relationships Between Physical Performance, Activity Levels, and Falls in Older Men.

Physical performance and activity have both been linked to fall risk, but the way they are jointly associated with falls is unclear. We investigated how these two factors are related to incident falls in older men. In 2,741 men (78.8 ± 5 years), we evaluated the associations between activity and physical performance and how they jointly contributed to incident falls. Activity was assessed by accelerometry. Physical performance was measured by gait speed, dynamic balance (narrow walk), chair stand time, grip strength, and leg power. Falls were ascertained by tri-annual questionnaires. Men were grouped into four categories based on activity and performance levels. The greatest number of falls (36%-43%) and the highest fall rate (4.7-5.4/y among those who fell) (depending on the performance test) occurred in men with low activity/low performance, but most falls (57%-64%) and relatively high fall rates (3.0-4.35/y) occurred in the other groups (low activity/high performance, high activity/high performance and high activity/low performance; 70% of men were in these groups). There were interactions between activity, performance (gait speed, narrow walk), and incident falls (p = .001-.02); predicted falls per year were highest in men with low activity/low performance, but there was also a peak of predicted falls in those with high activity. In community-dwelling older men, many falls occur in those with the lowest activity/worst physical performance but fall risk is also substantial with better activity and performance. Activity/physical performance assessments may improve identification of older men at risk of falls, and allow individualized approaches to prevention.

Effects of linear periodization versus daily undulating periodization on neuromuscular performance and activities of daily living in an elderly population.

Periodization is a systematic training calendar designed to provide variations in performance targeting, while maximizing results and reducing the potential for overtraining. When provided across multiple weeks, termed a mesocycle, it may also incorporate active recovery periods using specified drills designed to translate neuromuscular gains into targeted functional abilities. There are a number of models that can be used when applying periodization to resistance training (RT). Among the most common are the linear (LP) and daily fixed non-linear (NLP) models. It is currently unknown whether an optimal periodization strategy exists that will maximize benefits for older adults; therefore, we compared the impact of these two periodization models on neuromuscular and functional measures in a group of older persons living independently in the community. Thirty-six older adults, 58-80 years of age, were randomly assigned to either a LP (n = 16; 69.3 ± 4.6 y) or NLP (n = 14; 68.9 ± 6.7 y) group. The LP group performed 12 weeks of training comprised of separate 4-week strength and power training cycles, each followed by a 2-week recovery period incorporating translational exercises. The NLP group performed the strength, power, and translational training on three separate days during the week. Neuromuscular testing included seated chest press and leg press strength and power tests, while physical function testing included the gallon jug shelf test, laundry transfer test, floor stand-up, chair-to-stand test, and 8 foot timed up-and-go. 3 (time) × 2 (sex) × 2 (group) repeated measures ANOVA revealed both periodization strategies were equally effective at inducing neuromuscular and functional improvements and that men generally produced more strength and power than women. Both LP and NLP can be used to improve strength, power, and functional performance in healthy untrained older adults when strength, power and functional training cycles are involved. Therefore, personal preference and variety should be considered when deciding which approach to use, provided high-speed power and translational recovery components are included.

Forecasting the development of explosive leg power in youth soccer players

ABSTRACTPurpose: Monitoring athletic development in youth soccer can help sporting professionals monitor athletic development and evaluate the effectiveness of training interventions. However, long-term follow up in talent development programmes in youth soccer is complicated. Therefore, the aim of this study was to forecast the developmental trajectories of explosive leg power in youth soccer players. Methods: Mixed effects regression models were used to forecast explosive leg power (countermovement (CMJ) and standing broad jump (SBJ)) in a longitudinal sample of 2201 youth soccer players from two high level Belgian acedemies and the Belgian National teams. Players were aged between 6 and 20 years (mean age = 13.04 ± 3.18 y) and were subdivided into three age cohorts (6–10, 11–15, and 16–20 y) for CMJ and two age cohorts (6–16, and 17–20 y) for SBJ. Results: This study was able to accurately forecast explosive leg power using different regression equations in each age cohort. Conclusions: Researchers, coaches, and sporting professionals can use these methods to either predict future explosive leg power from current performance measures, monitor the development of explosive leg power, or assess the effectiveness of training interactions aimed at altering predicted developmental trajectories.

Functional Tests of Leg Muscle Strength and Power in Adults With Cystic Fibrosis.

Muscle weakness is an important systemic consequence in adults with cystic fibrosis, but it can be challenging to evaluate clinically. This study examined the validity of lower-extremity functional tests to assess quadriceps muscle strength and muscle power. The subjects underwent 4 functional tests: 30-s sit-to-stand test, stair-climb power test, vertical jump height, and triple hop distance. Quadriceps muscle strength and power were tested by using a dynamometer (the accepted standard). Quadriceps strength was measured from 5 maximum voluntary isometric contractions to obtain peak torque. Quadriceps power was evaluated from the peak power and peak velocity attained during isotonic contractions of the quadriceps at a preset load of 20% of the peak torque. Pearson correlations were used to determine associations between functional tests and accepted measures of quadriceps strength and power. Fifteen adults with cystic fibrosis (9 males; mean ± SD age, 32 ± 13 y; mean ± SD FEV1% predicted, 73 ± 19) completed the study. The stair-climb power test had the strongest correlations with peak torque (r = 0.84, P < .001) and power (r = 0.65, P = .009). Vertical jump height was moderately correlated with quadriceps strength (r = 0.62, P = .014) and quadriceps peak power (r = 0.51, P = .048). Similarly, triple hop distance had moderate correlations with quadriceps strength (r = 0.78, P = .001) and peak power (r = 0.57, P = .026). The sit-to-stand test was only associated with quadriceps strength (r = 0.55, P = .034). Functional tests can be applied clinically to measure leg muscle strength and power, with the stair-climb power test having the strongest associations with the standard measures. The utility of using functional tests to evaluate longitudinal changes in muscle function and its association with clinical outcomes should be examined in cystic fibrosis.