A Correlational Analysis of Tethered Swimming, Swim Sprint Performance and Dry-land Power Assessments

Propulsive forces in human competitive swimming: a systematic review on direct assessment methods

Human propulsive forces are a key-factor to enhance swimming performance, but there is scarce knowledge when using direct assessments. The aim of this review was to analyse the evidence about human propulsive forces in competitive swimming measured by direct assessment methods. A search up to 30 June 2020 was performed in Web of Science, PubMed, and Scopus databases. The Downs and Black Quality Assessment Checklist was used to assess the quality index (QI) of the included studies. Out of 2530 screened records, 35 articles met the inclusion criteria. Tethered-swimming and differential pressure sensors allow directly measure propulsive forces. Cross-sectional designs measured peak and mean propulsive force during the front crawl stroke and including men/boys (≥15 years-old) at different competitive levels were mostly reported. Men are more able to show higher propulsive forces than women counterparts. Short- and long-term effects were observed while using dry-land and in-water training programmes. The magnitude of propulsive force is dependent on the type of assessment method, swimming stroke, number of body limbs and gender. While the short-term effects supporting the different training programmes lead to an increase in propulsive force, there is a lack of long-term evidence.

Reliability of dynamic and isometric upper muscle strength testing in breast cancer survivors

Breast cancer is the most common cancer in women worldwide, and its treatment usually involves a combination of many medical procedures, including surgery, chemotherapy, radiotherapy, and hormonal therapy. One of the detrimental effects on physical function is reduced upper limb muscle strength. This study aimed to evaluate upper body strength intra-day and inter-day (test-retest) reliability using the handgrip strength test (HGS) and the bilateral isometric bench press (BIBP) and the test-retest reliability of the one repetition maximum on the bench press (BP-1RM) in breast cancer survivors (BCS). Thirty-two (52.94 ± 8.99 yrs) BCS participated in this study. The muscle strength tests were performed in two different moments, three to seven days apart. Intraclass coefficient correlation (ICC) and coefficient of variation (CV) were used to assess the reliability. Standard error of measurement (SEM), typical error of measurement (TEM), and minimally detectable change (MDC) analyses were performed. The Bland-Altman analysis was used to assess the agreement between test-retest. We found a reliability that can be described as "high" to "very high" (ICC ≥ 0.88; CV ≤ 10%) for intra-day and test-retest. SEM% and MDC% were lower than 5% and 11%, respectively, for all intra-day testing. SEM% and TEM% ranged from 3% to 11%, and MDC% ranged from 9% to 23% in the test-retest reliability. The agreement demonstrated a systematic bias ranging from 2.3% to 6.0% for all testing, and a lower systematic bias may be presented in the non-treated side assessed by HGS and BIBP. HGS, BIBP, and BP-1RM assessments are reliable for measuring upper-body muscle strength in BCS.

Which Strength Manifestation Is More Related to Regional Swimmers' Performance and In-Water Forces? Maximal Neuromuscular Capacities Versus Maximal Mechanical Maintenance Capacity

PURPOSE

To explore the association of the load-velocity (L-V) relationship variables and ability to maintain maximal mechanical performance during the prone bench-pull exercise with sprint swimming performance and in-water forces.

METHODS

Eleven competitive adult male swimmers (50-m front crawl World Aquatics points: 488 [66], performance level 4) performed 1 experimental session. The L-V relationship variables (L0 [ie,  maximal theoretical load at 0 velocity]; v0 [ie, maximal theoretical velocity at 0 load], and Aline [ie, area under the L-V relationship]) and maximal mechanical maintenance capacity were assessed at the beginning of the session. Afterward, sprint swimming performance and in-water force production were tested through a 50-m front-crawl all-out trial and 15-s fully-tethered swimming, respectively.

RESULTS

Only v0 presented high positive associations with 50-m time and swimming kinematics (r > .532; P < .046). The L0, v0, and Aline showed very high positive associations with the in-water forces during tethered swimming (r > .523; P < .049). However, the ability to maintain maximal mechanical performance, assessed by the mean velocity decline during the prone bench pull, was only significantly correlated with stroke rate (r = -.647; P = .016) and stroke index (r = .614; P = .022).

CONCLUSIONS

These findings indicate that maximal neuromuscular capacities, especially v0, have a stronger correlation with swimming performance and in-water force production than the ability to maintain maximal mechanical performance in level 4 swimmers.

From dry-land to the water: training and testing practices of strength and conditioning coaches in high level French sprint swimmers

Introduction

The aim of this study was to explore training and testing practices from Strength & Conditioning (S&C) coaches who manage groups of high-level French swimmers in elite training centers. The transfer of abilities from dry-land to in situ condition was also investigated.

Methods

24 French S&C coaches completed a survey via an online platform. Frequency analyses were made for quantitative and qualitative responses, the level of significance set for this study was p ≤ 0.05.

Results

Core stability, Strength & Power were the three most targeted qualities. Core strengthening in all its forms, Bench Press & Squat were the three most prescribed exercises. 79% of S&C coaches adapted exercises according to different parameters. Most of the coaches indicated that dry-land S&C sessions were preferentially placed before in-water sessions. Very varied exercises were used in-water to make the transfer from dry-land more effective. 87% of participants monitored the training load and 38% assessed the force and velocity parameters for some S&C exercises.

Discussion

Dry-land training practices of S&C coaches were mostly in line with scientific recommendations. In the light of results of the questionnaire, it would appear that testing procedures might be a key issue for transferring qualities from dry-land to in situ.

Dry-Land Force-Velocity, Power-Velocity, and Swimming-Specific Force Relation to Single and Repeated Sprint Swimming Performance

The aim of this study was to identify the relationship between dry-land and in-water strength with performance and kinematic variables in short-distance, middle-distance, and repeated sprint swimming. Fifteen competitive swimmers applied a bench press exercise to measure maximum strength (MS), maximum power (P), strength corresponding to P (F@P), maximum velocity (MV), and velocity corresponding to P (V@P) using F-V and P-V relationships. On a following day, swimmers performed a 10 s tethered swimming sprint (TF), and impulse was measured (IMP). On three separate days, swimmers performed (i) 50 and 100 m, (ii) 200 and 400 m, and (iii) 4 × 50 m front crawl sprint tests. Performance time (T), arm stroke rate (SR), arm stroke length (SL), and arm stroke index (SI) were calculated in all tests. Performance in short- and middle-distance tests and in 4 × 50 m training sets were related to dry-land MS, P, TF, and IMP (r = 0.51-0.83; p < 0.05). MS, P, and TF were related to SR in 50 m and SI in 50 and 100 m (r = 0.55-0.71; p < 0.05). A combination of dry-land P and in-water TF variables explains 80% of the 50 m performance time variation. Bench press power and tethered swimming force correlate with performance in short- and middle-distance tests and repeated sprint swimming.

The Effects of Incorporating Dry-land Short Intervals to Long Aerobic-dominant In-Water Swimming Training on Physiological Parameters, Hormonal Factors, and Performance: A Randomized-Controlled Intervention Study

This study investigated the impact of a 4-week dry-land short sprint interval program (sSIT) on a swim ergometer, when incorporated into long aerobic-dominant in-water swimming training, on the physiological parameters, hormonal factors, and swimming performance of well-trained swimmers. Sixteen participants (age = 25 ± 6 years, height = 183 ± 6 cm, weight 78 ± 6 kg, body fat = 10.6 ± 3.1%) were randomized to either a long aerobic-dominant in-pool training plus three sessions/week of sSIT or a control group (CON) who didn't engage in SIT. sSIT consisted of 3 sets of 10 × 4 s, 10 × 6 s, and 10 × 8 s all-out sprints interspersed by 15, 60, and 40 s recovery between each sprint, respectively. Pre- and post-training assessments included peak oxygen uptake (V̇O2peak), O2pulse (V̇O2/HR), ventilation at V̇O2peak (V̇E@V̇O2peak), peak and average power output, and freestyle swim performance at 50, 100, and 200-m distances, stroke rate, as well as testosterone and cortisol. sSIT resulted in significant improvements in V̇O2peak (5.8%), O2pulse (4.7%), V̇E@V̇O2peak (7.1%), peak and average power output (6.7% and 13.8%, respectively), total testosterone (20%), testosterone to cortisol ratio (16.1%), and 50, 100, and 200-m freestyle swimming performance (-2.2%, -1.2%, and -1.1%, respectively). Furthermore, the observed alterations in the physiological, biochemical, and performance adaptations were significantly more substantial in the sSIT group than the CON group (p ≤ 0.05), demonstrating no modifications during the 4-week long aerobic-dominant in-water swimming without sSIT. The current research effectively established that supplementing standard long aerobic-dominant in-water swim training with three weekly dry-land sSIT sessions triggers adaptive mechanisms that foster enhancements in the aerobic and anaerobic capacity and swimming performance in well-trained swimmers.

Reliability of using a pressure sensor system to measure in-water force in young competitive swimmers

The aim of this study was to analyze the reliability of using a differential pressure system to measure in-water force in young competitive swimmers. Ten boys and five girls (12.38 ± 0.48 years, 49.13 ± 6.82 kg, 159.71 ± 7.99 cm) were randomly assigned to perform two maximum bouts of 25 m front crawl on different days (trial one, T1; trial two, T2), one week apart. A differential pressure system composed of two hand sensors (Aquanex System, v.4.1, Model DU2, Type A, Swimming Technology Research, Richmond, VA, United States) was used to measure the peak (RFPEAK) and the mean (RFMEAN) resultant force of the dominant and non-dominant hands (in Newton, N). Reliability was analyzed by computing the intraclass correlation coefficient (ICC), typical error (TE), smallest worthwhile change (SWC), coefficient of variation (CV%), standard error of measurement (SEM), and the minimal detectable change (MDC). Bland-Altman plots with 95% limits of agreement were also analyzed. The results showed no differences between T1 and T2 in all variables (p > 0.05). The ICC showed "excellent" reliability (ICC > 0.90) for the RFPEAK and RFMEAN in both hands. The CV% was rated as "good" (<5%) and TE was smaller than SWC in all variables. The Bland-Altman plots showed high reliability with a small bias (RFPEAK dominant, -0.29 N; RFPEAK non-dominant, -0.83 N; RFMEAN dominant, 0.03 N; RFMEAN non-dominant, 0.50 N). The pressure sensor system (Aquanex System) seems to be a reliable device for measuring the hand resultant force during front crawl in young swimmers and can be used to monitor the changes over time.

Gender Differences and the Influence of Body Composition on Land and Pool-Based Assessments of Anaerobic Power and Capacity

Consistent differences between males and females have been shown in land-based measurements of anaerobic power and capacity. However, these differences have not been investigated for a tethered 30-s maximal swimming test (TST). The purpose of this study is to explore gender differences in land and pool-based assessments of anaerobic power (Fpeak) and capacity (Fmean), as well as the influence of body composition. Thirteen males and fifteen females completed land (Wingate (WAnT)) and pool-based (TST) measures of anaerobic power and capacity previously described in the literature. Additionally, the subjects completed assessments of body composition via air displacement plethysmography. The males produced higher force than the females for Fpeak (p < 0.001) and Fmean (p = 0.008) during the TST. However, linear regression analysis determined that lean mass significantly predicted Fpeak (p = 0.002) and Fmean (p < 0.001) during the TST, while gender was no longer significant (p = 0.694 and p = 0.136, respectively). In conclusion, increases in anaerobic power and capacity (Fpeak and Fmean) may be a function of increased lean mass in males and females, warranting future research on the impact of resistance training programs on force production and swimming performance.

Comparison between Dry-Land and Swimming Priming on 50 m Crawl Performance in Well-Trained Adolescent Swimmers

The purpose of the study was to investigate the effect of dry-land priming (DLP) versus swimming priming (SP) on the 50 m crawl performance of well-trained adolescent swimmers. Thirteen adolescent swimmers were randomly assigned to perform either a DLP or SP 24 h prior to a 50 m sprint crawl time-trial. Baseline measurements included a 50 m sprint crawl time-trial as a control (C) condition, the evaluation of body composition, countermovement jump (CMJ), isometric peak torque (IPT), and rate of torque development (RTD). Rating of perceived exertion (RPE) was obtained following the DLP and SP programs. Both DLP and SP significantly decreased the 50 m crawl time-trial, by −2.51 ± 2.43% and −2.59 ± 1.89% (p < 0.01), respectively, compared with the C time-trial. RPE was not different between DLP and SP (p = 0.919). CMJ performance remained unchanged after DLP and SP programs compared with the C trial (p > 0.05). The percentage decrease in the 50 m crawl after DLP was significantly correlated with the percentage decrease in the 50 m crawl following SP (r = 0.720, p = 0.006). CMJ power, lean body mass, IPT, and RTD were significantly correlated with 50 m crawl performance. These results suggest that both DLP and SP strategies, when applied 24 h prior to a 50 m crawl time-trial, may enhance performance in well-trained adolescent swimmers.

Acute and Long-Term Effects of Concurrent Resistance and Swimming Training on Swimming Performance

Dry-land resistance exercise (RT) is routinely applied concurrent to swimming (SWIM) training sessions in a year-round training plan. To date, the impact of the acute effect of RT on SWIM or SWIM on RT performance and the long-term RT-SWIM or SWIM-RT training outcome has received limited attention. The existing studies indicate that acute RT or SWIM training may temporarily decrease subsequent muscle function. Concurrent application of RT-SWIM or SWIM-RT may induce similar physiological alterations. Such alterations are dependent on the recovery duration between sessions. Considering the long-term effects of RT-SWIM, the limited existing data present improvements in front crawl swimming performance, dry-land upper and lower body maximum strength, and peak power in swim turn. Accordingly, SWIM-RT training order induces swimming performance improvements in front crawl and increments in maximum dry-land upper and lower body strength. Concurrent application of RT-SWIM or SWIM-RT training applied within a training day leads in similar performance gains after six to twelve weeks of training. The current review suggests that recovery duration between RT and SWIM is a predisposing factor that may determine the training outcome. Competitive swimmers may benefit after concurrent application with both training order scenarios during a training cycle.

Inter-Limb Jump Asymmetries and Their Association with Sport-Specific Performance in Young Male and Female Swimmers

This study aimed to examine inter-limb jump asymmetries and their association with sport-specific performance in young swimmers. Thirty-eight (male, n = 19; female, n = 19) regional/national level young swimmers (age: 12.3 ± 1.2 years; height: 159.6 ± 8.2 cm; body mass: 52.5 ± 9.2 kg) participated in this study. Inter-limb asymmetries were assessed for single-leg countermovement jump (_SLCMJ) and single-leg standing long jump (_SLSLJ). Sport-specific performance was evaluated using front crawl (i.e., 50 m and 25 m) and front crawl kick (i.e., 50 m and 25 m). The kappa coefficient revealed a "slight" level of agreement (Κ = 0.156, 0.184, and 0.197 for female, male, and all, respectively) between the direction of asymmetry for _SLCMJ and _SLSLJ, indicating that asymmetries rarely favored the same limb during both tests. A paired sample t-test showed a significant difference (p = 0.025) between asymmetry scores obtained in _SLCMJ and _SLSLJ. No significant difference was found in asymmetry scores between males and females (p = 0.099 to 0.977). Additionally, no association between asymmetry scores and sport-specific performance was observed (p > 0.05). Our findings highlight the independent nature of inter-limb asymmetries derived from _SLCMJ and _SLSLJ among young male and female swimmers. Further, our results suggest no association between jumping asymmetries and sport-specific performance.

Thermal Imaging of Exercise-Associated Skin Temperature Changes in Swimmers Subjected to 2-min Intensive Exercise on a VASA Swim Bench Ergometer

An important element of swimming training is the improvement of muscle strength and the technique of swimming movements on dry land. The heat generated by the muscles involved in the effort contributes to a change in the temperature of the skin surface, which can be assessed by the IRT method. The aim of the study was to assess the symmetry and dynamics of changes in surface temperatures of selected areas of the body in swimmers after exercise on a swimming ergometer with the use of IRT. A total of 12 swimmers (aged 19 ± 1.3 years) completed a two-minute stress test (front crawl swimming movements) using a VASA Swim Ergometer, with a load of 5. Using an IRT camera (FLIR E60), postexercise changes in back and upper limbs surface temperature in relation to the resting values were observed. After exercise, the temperature value of all assessed areas decreased, apparently in the area of the back and the back of the arms, returning to the baseline values after 12 min of observation. There was no asymmetry in mean temperature values between the right and left upper limbs. IRT is a noninvasive and sensitive tool for the individual analysis of changes in body surface temperature in swimmers after training on dry land.

Specific and Holistic Predictors of Sprint Front Crawl Swimming Performance

The aim of the study was to examine the impact of selected water- and dry-land predictors of 50-m front crawl performance among 27 male swimmers aged 19.3 ± 2.67 years. The following water tests were performed: front crawl tethered arm stroking in a water flume (flow velocity: 0.9 m·s-1) and leg tethered flutter kicking in a swimming pool. Anaerobic tests on dry land included arm cranking and a set of 10 countermovement jumps. The maximal and average forces generated by legs in tethered swimming (Fl max and Fl ave) turned out to be the strongest predictors of sprint swimming aptitude. These values were strongly correlated with total speed (Vtotal50) (r = 0.49, p < 0.05 and r = 0.54, p < 0.01, respectively), start, turn, and finishing speed (VSTF) (r = 0.60, p < 0.01 and r = 0.67, p < 0.01, respectively). The relationship of Fl max and Fl ave with surface speed (Vsurface) was moderate (r = 0.33, non-significant and r = 0.41, p < 0.05, respectively). The maximal force generated by arms (Fa max) during flume tethered swimming significantly influenced Vsurface and Vtotal50 (0.51, p < 0.01 and 0.47, p < 0.05, respectively). Its relationship with VSTF was close to significant (0.36, p = 0.07). Upper and lower limb dry-land tests showed lower and more holistic relationships with the 50-m front crawl race, however, being a good complement to overall fitness assessment. Specific in-water evaluation, especially the newly prepared flutter kicking test, as well as dry-land tests, can be applied to regularly monitor progress in swimming training, and to identify talented swimmers.

The impact of a single surfing paddling cycle on fatigue and energy cost

Surfing is one additional sport proposed by the Tokyo 2020 Organizing Committee. Surprisingly, substantial efforts to understand surfing energetics are recent, and the impact of a single surfing paddling cycle on fatigue and energy cost is still not clear. Since surfing paddling technique is highly specific, experiments in real practice conditions are necessary to provide deeper insights. Through a biophysical approach, biomechanical and energetics responses of surfing paddling were quantified and compared from 16 competitive male surfers (23.5 ± 10.0 years old, 65.3 ± 11.4 kg and 1.72 ± 0.01 m) during two sets (PRE and POST) of 10 s all-out tethered paddling plus 20 m sprint paddling, interposed by 6 min of endurance paddling. Faster surfers presented lower energy cost during sprint PRE (r² = 0.30, p = 0.03) and endurance (r² = 0.35, p = 0.02) relative surfing paddling velocities. Although the energy cost was higher for a lower velocity at maximal paddling velocity POST, the energy cost of surfing paddling increased with absolute velocity according to a power function (R² = 0.83). Our results suggest that fatigue seems to occur even following a single surfing paddling cycle. Developing a powerful and endurable metabolic base while reducing energy cost during surfing paddling should be seen as key factors in surfing training programs.

The Relationship Between Selected Load-Velocity Profile Parameters and 50 m Front Crawl Swimming Performance

The purpose of the present study was to establish relationships between sprint front crawl performance and a swimming load-velocity profile. Fourteen male national-level swimmers performed 50 m front crawl and semi-tethered swimming with three progressive loads. The 50 m performance was recorded with a multi-camera system, with which two-dimensional head displacement and the beginning of each arm-stroke motion were quantified. Forward velocity (V_50m), stroke length (SL) and frequency (SF) were quantified for each cycle, and the mean value of all cycles, excluding the first and last cycles, was used for the analysis. From the semi-tethered swimming test, the mean velocity during three stroke cycles in mid-pool was calculated and plotted as a function of the external load, and a linear regression line expressing the relationship between the load and velocity was established for each swimmer. The intercepts between the established line and the axes of the plot were defined as theoretical maximum velocity (V₀) and load (L₀). Large to very large correlations were observed between V_50m and all variables derived from the load-velocity profiling; L₀ (R = 0.632, p = 0.015), L₀ normalized by body mass (R = 0.743, p = 0.002), V₀ (R = 0.698, p = 0.006), and the slope (R = 0.541, p < 0.046). No significant relationships of SL and SL with V_50m and the load-velocity variables were observed, suggesting that each swimmer has his own strategy to achieve the highest swimming velocity. The findings suggest that load-velocity profiling can be used to assess swimming-specific strength and velocity capabilities related to sprint front crawl performance.

SwimOne. New Device for Determining Instantaneous Power and Propulsive Forces in Swimming

The propulsive forces and instantaneous power that are generated by a swimmer have a great influence on the swimming performance. This works presents a new device, called SwimOne, for measuring propulsive force and estimating the instantaneous power of the swimmer. In addition, the detailed prototype is able to exert a customizable opposition force to the swimmer for training purpose. The conceptual idea is presented by describing the differential equation of the swimmer and the protocol for a factible estimation of the instantaneous power. The variables that are to be measured and estimated are identified and, consequently, the sensor and actuator systems can be selected. The high-level and detailed designs of the prototype are presented together with the protocol that is carried out in order to validate the sensor and actuation systems. The device is able to monitor the variables of interest of the swimmer together with the propulsive force and instant power. Finally, some experiments are carried out providing the results of several participants swimming in crawl, backstroke, butterfly, and breaststroke styles in the presence of different opposition force. The preliminary results show that SwimOne is valid for measuring instantaneous force and power with different loads in swimming.

A Comparison between Elite Swimmers and Kayakers on Upper Body Push and Pull Strength and Power Performance

The aim of the present study was to compare the load-power curve expressed at bench press (PR) and prone bench pull (PU) between elite swimmers and kayakers. Another aim was to calculate the strength and power PR/PU ratio in the same populations. Fifteen elite swimmers (SW: age = 23.8 ± 2.9 y; body mass = 82.8 ± 5.6 kg; body height = 184.1 ± 4.6 cm) and 13 elite kayakers (KA: age = 23.8 ± 2.9 y; body mass = 91.0 ± 3.5 kg; body height = 180.1 ± 5.4 cm) were assessed for PR 1RM and PU 1RM. They were then assessed for power produced at 40, 60 and 80% of 1RM in both PR and PU. The area under the load-power curve (AUC) and PR/PU ratios were calculated for both the SW and KA groups. The KA group showed significantly higher PR1RM (+18.2%; p = 0.002) and PU1RM (+25.7%; p < 0.001) compared to the SW group. Significant group differences were also detected for PUAUC (p < 0.001) and for the PR/PU power ratio (p < 0.001). No significant group differences were detected for PRAUC (p = 0.605) and for the PR/PU strength ratio (p = 0.065; 0.87 and 0.82 in SW and KA, respectively). The present findings indicate that elite KA were stronger and more powerful than elite SW in the upper body. Not consistently with other athletic populations, both KA and SW athletes were stronger and more powerful in upper body pull compared to push moves.

The effects of dry-land strength training on competitive sprinter swimmers

Background/objective

This study aimed to examine the effects of eight weeks of dry-land strength combined with swimming training on the development of upper and lower body strength, jumping ability, and swimming performance in competitive sprinter swimmers.

Methods

Twenty (14 men and 6 women) university swimmers of national-level (age: 20.55 ± 1.76 years, body mass: 68.86 ± 7.69 kg, height: 1.77 ± 0.06 m, 100 m front crawl: 71.08 ± 6.71s, 50 m front crawl: 31.70 ± 2.45s) were randomly divided into two groups: experimental group (EG: 11) and control group (CG: 9). In addition to the usual in-water training (3–4 sessions per week of ∼80 min), the EG performed 8 weeks (one session per week) of strength-training (ST). The ST included bench press, full squat, countermovement jumping, countermovement jumping with free-arm movement, and the medical ball throwing. Stroke length, stroke frequency, stroke index, and swimming velocity were recorded during 50 and 100 m front crawl time-trials. Strength and swimming performance were evaluated before and after 8 weeks of training.

Results

The results showed a significant improvement in sprint performance (50 m: p < 0.01, d = 0.47; 100 m: p < 0.05, d = 0.42), stroke frequency (50 m: p < 0.01, d = 0.90) and stroke index (100 m: p < 0.01, d = 0.29) in the EG. Despite both groups’ increased strength performance, increases in bench press were higher in the EG (p < 0.001, d = 0.75) than CG (p = 0.05, d = 0.34).

Conclusions

Complementing in-water training with strength training seems to be relevant to improve upper body strength and to optimize 50 m and 100 m swimming performance, adapting technical patterns used during all-out swimming.

In-Season Strength Training in Elite Junior Swimmers: The Role of the Low-Volume, High-Velocity Training on Swimming Performance

The aim of this study was to analyze the effect of long-term combined strength training (ST) and plyometrics on strength, power and swimming performances in elite junior swimmers during a competitive season. Ten elite junior swimmers (5 women and 5 men) completed the study (age: 16.6 ± 0.7 years; mass: 62.2 ± 5.4 kg; stature: 1.70 ± 0.07 m). The participants trained twice a week during 20 weeks. The ST program consisted of upper- and lower limbs exercises with low loads and low volume, lifting the load at maximal intended velocity. The effect of the training protocol was assessed using the 1RM in the full squat (SQ) and bench press (BP), jump height (CMJ), the maximal number of repetitions completed in the pull-up (PU) exercise and time during 50-m freestyle. Training program resulted in significant improvements in CMJ (12.1%, ES: 0.57), maximal dynamic strength in the SQ (16.4%, ES: 0.46) and BP (12.1%, ES: 0.34) exercises, the maximum number of repetitions completed during the PU test (90.7%, ES: 0.57) and swimming performance (-3.9%, ES: 0.45). There were no significant differences between both genders. The relative changes in swimming performance showed significant relationship with the relative changes in 1RM of SQ for pooled data (r=-0.66, p<0.05) and the relative changes in the PU exercise in female swimmers (r=-0.99, p<0.05). Therefore, coaches and strength and conditioning professionals should consider including in-season dry-land ST programs within the training routine in order to obtain further improvements in swimming performance.

In-Water and On-Land Swimmers' Symmetry and Force Production

Although performance and biomechanical evaluations are becoming more swimming-specific, dryland testing permits monitoring of a larger number of performance-related variables. However, as the degree of comparability of measurements conducted in-water and on land conditions is unclear, we aimed to assess the differences between force production in these two different conditions. Twelve elite swimmers performed a 30 s tethered swimming test and four isokinetic tests (shoulder and knee extension at 90 and 300°/s) to assess peak force, peak and average torque, and power symmetry index. We observed contralateral symmetry in all the tests performed, e.g., for 30 s tethered swimming and peak torque shoulder extension at 90°/s: 178 ± 50 vs. 183 ± 56 N (p = 0.38) and 95 ± 37 vs. 94 ± 35 N × m (p = 0.52). Moderate to very large direct relationships were evident between dryland testing and swimming force production (r = 0.62 to 0.96; p < 0.05). Swimmers maintained similar symmetry index values independently of the testing conditions (r = −0.06 to −0.41 and 0.04 to 0.44; p = 0.18–0.88). Asymmetries in water seems to be more related to technical constraints than muscular imbalances, but swimmers that displayed higher propulsive forces were the ones with greater force values on land. Thus, tethered swimming and isokinetic evaluations are useful for assessing muscular imbalances regarding propulsive force production and technical asymmetries.

A Review of Countermovement and Squat Jump Testing Methods in the Context of Public Health Examination in Adolescence: Reliability and Feasibility of Current Testing Procedures

BACKGROUND

In the context of a public health physical fitness (PF) examination in adolescence, a countermovement jump (CMJ) and a squat jump (SJ) are two vertical jump (VJ) tests widely used to evaluate lower limb muscle strength and power, respectively. The main criticism of both the CMJ and SJ test is the lack of test standardization. Therefore, the objectives of this review are: (a) to gather information about both jumps; (b) to investigate whether it is possible to identify common procedures referred to in the CMJ and SJ technical execution, and (c) to design standard operating procedures (SOPs) to promote CMJ and SJ standardization in an adolescent population aged 12-18 years.

METHODS

The review partially adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA). Due to growing attention in monitoring physical health through field tests in recent years, articles were collected using the PubMed, Web of Science, and Scopus databases from January 2009 to July 2019. Original articles in which CMJ or SJ were used to assess the muscular strength in adolescents were eligible for further analysis. Articles written in English was imposed as a limit.

RESULTS

A total of 117 studies met the inclusion criteria. The description of the CMJ and SJ test procedures was different within the literature, with discrepancies in the jump technique, number of jumps, and measurement devices used.

CONCLUSIONS

A lack of method standardization for both the CMJ and the SJ test was identified. Based on the literature, SOPs for both VJs were proposed. These are useful in the context of public health PF examination in adolescents, as they facilitate an unbiased comparison of jump performance data between published studies.

Jump-Squat and Half-Squat Exercises: Selective Influences on Speed-Power Performance of Elite Rugby Sevens Players

The aim of this study was to evaluate the relation between the maximum mean propulsive power (MPP) obtained in the loaded jump squat (JS) and half squat (HS) exercises and functional performances in vertical jumps, 40 m linear speed (VEL) and change-of-direction (COD) tests, using the median split technique. Twenty-two male rugby sevens players from the Brazilian National Olympic Team (Rio-2016) performed vertical jumping tests (squat and countermovement jumps [SJ and CMJ]), JS and HS exercises, COD speed test and sprinting velocity in 40 m, in this order. Based on the results of the MPP in the JS and HS exercises the participants were divided, using the median split, into four groups as follows: higher JS, lower JS, higher HS, and lower HS. Between-group differences in the functional tasks were detected via magnitude-based inferences. The athletes with higher MPP in the JS were capable of jumping higher and sprinting faster (including the COD speed test) than their weaker counterparts. This pattern was not observed in the HS exercise. To conclude, JS was shown to be more connected to sprinting, COD speed and jumping abilities than HS in elite rugby sevens players and should be preferred for assessing and possibly training elite athletes needing to improve speed-power related abilities.

Improving Sprint Performance in Soccer: Effectiveness of Jump Squat and Olympic Push Press Exercises

Training at the optimum power load (OPL) is an effective way to improve neuromuscular abilities of highly trained athletes. The purpose of this study was to test the effects of training using the jump squat (JS) or Olympic push-press (OPP) exercises at the OPL during a short-term preseason on speed-power related abilities in high-level under-20 soccer players. The players were divided into two training groups: JS group (JSG) and OPP group (OPPG). Both groups undertook 12 power-oriented sessions, using solely JS or OPP exercises. Pre- and post-6 weeks of training, athletes performed squat jump (SJ), countermovement jump (CMJ), sprinting speed (5, 10, 20 and 30 m), change of direction (COD) and speed tests. To calculate the transfer effect coefficient (TEC) between JS and MPP OPP and the speed in 5, 10, 20, and 30 m, the ratio between the result gain (effect size [ES]) in the untrained exercise and result gain in the trained exercise was calculated. Magnitude based inference and ES were used to test the meaningful effects. The TEC between JS and VEL 5, 10, 20, and 30 m ranged from 0.77 to 1.29, while the only TEC which could be calculated between OPP and VEL 5 was rather low (0.2). In addition, the training effects of JS on jumping and speed related abilities were superior (ES ranging from small to large) to those caused by OPP (trivial ES). To conclude, the JS exercise is superior to the OPP for improving speed-power abilities in elite young soccer players.