Reliability of Load-Velocity Profiling in Front Crawl Swimming

Factors Relating to Sprint Swimming Performance: A Systematic Review

BACKGROUND

Swimming performance depends on a wide variety of factors; however, the interaction between these factors and their importance varies between events. In sprint events, the characterized pacing underlines its specific development, as swimmers must achieve the highest possible speed while sustaining it to the greatest extent possible.

OBJECTIVES

The aim of this review was to identify the key factors underlying sprint swimming performance and to provide in-depth and practical evidence-based information to optimize performance.

METHODS

The review protocol was not registered. PubMed, Web of Science and Scopus databases were searched up to October 31, 2023. Studies involving competitive swimmers and investigating sprint swimming performance were included, while studies conducted with young or masters' swimmers, triathletes or waterpolo players or not investigating sprint swimming performance were excluded. The Downs and Black Quality Assessment Checklist was performed on the included articles to assess the methodological quality.

RESULTS

After applying the PICOS framework, 39 of the 1330 articles initially identified were included according to the PRISMA guidelines. The included records focused mainly on dry-land strength and in-water forces of both upper and lower limbs. A wide range of kinematic variables were also examined, together with the importance of anthropometric and various physiological parameters.

CONCLUSION

This review highlights the importance of developing muscular strength and effectively transferring it to performance in the water. The evidence suggests that muscular development should prioritize enhancing velocity and effective displacement, rather than merely increasing force and performance in loaded tests. However, further research is needed to confirm this. While in-water forces have been well studied, there is a notable lack of analysis regarding drag. The optimal balance between stroke rate and stroke length should be determined individually, with a primary focus on achieving a high stroke length from a high stroke rate. Although anthropometry may play an important role in performance, the interaction of these traits appears to be complex, suggesting that other factors may be more important in determining performance outcomes. From a physiological perspective, the results indicate that the lactate peak and rate of accumulation should be thoroughly developed. Notwithstanding, this review shows the lack of a solid body of knowledge on the importance of anaerobic and especially aerobic factors. Finally, the absence of a list of potential confounders, together with the lack of high-quality studies involving elite swimmers (level 1 and 2), complicates the interpretation of the results.

The Load-Velocity Slope Is an Indicator of the Active Drag in All Competitive Swimming Strokes

INTRODUCTION

Active drag in swimming is a critical variable that affects swimmers' performance, as well as the physiological load, but it is challenging for practitioners to assess this variable. This study aimed to assess if the load-velocity profiling method can be used as an indicator of active drag.

METHODS

A total of 419 swimmers performed three semitethered swimming trials in their speciality among the four competitive strokes with different external loads. Linear regression between external load and swimming velocity, as well as the external load relative to the body mass and swimming velocity, were established. The active drag and drag coefficient of each swimmer were calculated using a velocity perturbation method.

RESULTS

There were significant correlations of the active drag with the absolute slope ( correlation coefficient ≥ 0.696, P < 0.001) and relative slope ( correlation coefficient ≥ 0.538, P < 0.001) in all four strokes and both sexes. A multiple regression analysis exhibited that the primary determinant of these relationships was the drag coefficient (semipartial correlation ≥0.422, P < 0.001). The effects of the height and body mass index (BMI) on the relationship between the drag and the absolute slope were small (0.195 ≤ semipartial correlation ≤0.249, P < 0.001), which became either nonsignificant (height: P ≥ 0.282) or trivial (BMI: -0.099 ≤ semipartial correlation ≤ -0.081, P ≤ 0.011) when focusing on the relative slope.

CONCLUSIONS

These results indicate that the absolute load-velocity slope is a strong indicator of the active drag, and the relative slope is useful when indirectly assessing the drag coefficient.

The relationship between maximal lactate accumulation rate and sprint performance parameters in male competitive swimmers

This study aimed to examine the relationship between the maximal lactate accumulation rate (ċLamax) and sprint performance parameters in male competitive swimmers. Seventeen male competitive swimmers volunteered to perform a 20 m maximal front crawl sprint without pushing off the wall from a floating position. ċLamax was determined by the 20-m sprint time and blood lactate measured before and after the 20 m sprint. For the sprint performance parameter, a 50 m time trial with the front crawl swimming stroke was conducted, and the times taken from 0 to 15 m, 15-25 m, 25-35 m, and 35-45 m were analyzed. A semi-tethered swimming test was conducted to investigate the load-velocity profile of each swimmer. From the load-velocity profile, theoretical maximal velocity (V0), maximal load (L0) and relative maximal load (rL0) were examined. The slope of the load-velocity profile was also determined. According to the results, ċLamax correlated with 50 m front crawl performance (r = -.546, p < .05). Moreover, a higher ċLamax was related to faster 0-35 m section time. Furthermore, ċLamax correlated with L0 (r = .837, p < .01), rL0 (r = .820, p < .01), and load-velocity slope (r = .804, p < .01). ċLamax is a good indicator of 50 m front crawl performance in male swimmers, and higher glycolytic power contributes to the faster time at the beginning of the sprint race. ċLamax could also evaluate the ability of a swimmer to apply force to the water during high-intensity swimming.

The relationship between load-velocity profiles and 50 m breaststroke performance in national-level male swimmers

This study investigated the relationships between load-velocity profiling and 50 m breaststroke performance. Twenty-seven male swimmers qualified for the national championship participated and performed a 50 m breaststroke trial with a multicamera system. The total race time (t50 m), forward velocity during surface swimming (v50 m), stroke length, and stroke frequency were obtained from the automatic post-processing of the system. Afterwards, the participants performed semi-tethered swimming with three external loads using a robotic resistance device. The average velocity from three stroke cycles was plotted as a function of the corresponding load. The theoretical maximum velocity (v0) and load (L0), L0 normalized to body mass, steepness of the regression line (slope), and active drag (AD) were calculated. The main findings were moderate to large correlations of two 50 m race variables (t50 m and v50 m) with v0, L0, and AD (t50 m range: r = -.444 to r = -.619, p = .020 to p = .001), (v50 m range: r = .451 to r = .568, p = .018 to p = .002). This shows the importance of applying maximum propulsive force to achieve high swimming performance and that load-velocity profiling is an indicator of 50 m breaststroke performance. Load-velocity measurements over time can also monitor velocity, strength, and drag-minimizing abilities, explaining performance changes and training effects.

Lower and upper extremity contributions to propulsion and resistance during semi-tethered load-velocity profiling in front crawl swimming

The study estimated lower and upper extremity contributions to whole-body front crawl swimming using semi-tethered load-velocity profiling. Nine female and 11 male (inter)national-level swimmers performed 20 m semi-tethered sprints, each with five progressive loads for lower (leg kicking), upper (arm stroke), and whole-body front crawl movements. The theoretical maximal speed (v0) and load (L0), and active drag (Da) were expressed as a percentage of the sum of both extremities for the movements of each extremity to calculate their contributions. The difference of whole-body values minus the sum of both extremities was used to estimate whole-body reserves. Lower (upper) body contributions were 43.8 ± 2.8% (56.2%) for v0, 37.3 ± 7.1% (62.7%) for L0, and 39.6 ± 5.6% (60.4%) for Da. Statistically significant whole-body reserves were found for v0 (-30.9 ± 3.9%, p < 0.001) and Da (-5.7 ± 11.7%, p = 0.04). V0 reserves correlated very highly with whole-body v0 in males (r = 0.71, p = 0.014) and moderately in females (r = 0.47, p = 0.21). The lower extremities contribute substantially to front crawl load-velocity profiles of highly trained swimmers. Higher sprint swimming speeds are associated with an efficient speed transfer from lower- and upper- to whole-body movement.

Load-Velocity Profile and Active Drag in Young Female Swimmers: An Age-Group Comparison

PURPOSE

The present study aimed to establish differences in load-velocity profiling, active drag (AD), and drag coefficient (Cd) between 3 age groups of female swimmers.

METHODS

Thirty-three swimmers (11, 13, or 16 y old) were recruited. The individual load-velocity profile was determined for the 4 competitive swimming strokes. The maximal velocity (V0), maximal load (L0), L0 normalized to the body mass, AD, and Cd were compared between the groups. A 2-way analysis of variance and correlation analysis were conducted.

RESULTS

Compared with their younger counterparts, 16-year-old swimmers generally had larger V0, L0, and AD, which was particularly evident when comparing them with 11-year-old swimmers (P ≤ .052). The exception was breaststroke, where no differences were observed in L0 and AD and Cd was smaller in the 16-year-old group than the 11-year-old group (P = .03). There was a negative correlation between Cd and V0 for all groups in backstroke (P ≤ .038) and for the 11-year-old group and 13-year-old group in breaststroke (P ≤ .022) and front crawl (P ≤ .010). For the 16-year-old group, large correlations with V0 were observed for L0, L0 normalized to the body mass, and AD (P ≤ .010) in breaststroke and for L0 and AD with V0 in front crawl (P ≤ .042). In butterfly, large negative correlations with V0 were observed in the 13-year-old group for all parameters (P ≤ .027).

CONCLUSIONS

Greater propulsive force is likely the factor that differentiates the oldest age group from the younger groups, except for breaststroke, where a lower Cd (implying a better technique) is evident in the oldest group.

Utility of Novel Rotational Load-Velocity Profiling Methods in Collegiate Softball Players

ABSTRACT

Herring, CH, Beyer, KS, Redd, MJ, Stout, JR, and Fukuda, DH. Utility of novel rotational load-velocity profiling methods in collegiate softball players. J Strength Cond Res 38(1): 136-145, 2024-The purpose of this study was to determine the reliability of bat swing (BS) and rotational medicine ball throw (RMBT) load-velocity profiling (LVP) methods and explore relationships with batting performance in NCAA Division I softball players. Bat velocity was tracked with a swing sensor during the BS method, whereas an inertial measurement unit (IMU) tracked forearm velocity during the BS and RMBT methods. Intraclass correlation coefficients (ICC) were used for relative reliability, and coefficient of variation (CV) was used for absolute reliability. With the exception of theoretical maximum velocity (V0) using the average of top 2 peak velocities (PVavg) during the RMBT, no LVP variables were found to be reliable during the RMBT or BS method using the IMU (ICC ≤0.7; CV ≥15%). For the BS method with the swing sensor, all bat loads and V0 had acceptable reliability using peak velocity (PV) and PVavg (ICC >0.7; CV <15%), whereas all LVP variables were highly related between the multiple-load and two-load models when using PV and PVavg (r = 0.915-0.988; p < 0.01). There were significant relationships (r = 0.603-0.671; p < 0.05) between PV using the 0.99 Kg bat load and V0, and several in-game batting statistics. Practitioners may use the BS with the swing sensor as a rotational LVP assessment, although they should be cautious of aiming to improve batting performance in collegiate softball players based on the correlations reported until further research is performed.

Associations between load-velocity profiling and race parameters of elite swimmers in the 100 and 200m freestyle events

Introduction

Improving swimming performance involves assessments of biomechanical variables of the stroke, and it can be achieved using semi-tethered swimming tests. The aim of this study was thus to investigate the associations between load-velocity (L-V) profiles, from a semi-tethered swimming protocol and race variables in the 100 m and 200 m freestyle events.

Methods

Eight swimmers completed a L-V profiling protocol consisting of four sprints (25 m, 25 m, 20 m, 15 m) against increasing loads (0.1, 2.0, 4.0, 6.0 kg respectively) with complete recovery between repetitions (>5 min). The L-V linear regression was used to estimate maximal velocity (V0) and body mass normalized load (rL0). Race variables such as clean swimming speed (V), stroke rate (SR), distance per cycle (SL) and stroke index (SI) were assessed from video analysis of 100 m and 200 m freestyle events taking place 3-4 days after the L-V protocol.

Results

L-V results showed high levels of speed (mean ± SD: 1.87 ± 0.04 m/s) and heavy maximal relative loads (mean ± SD: 38.5 ± 6.51 as % of body mass). Swimmers also achieved high-level performances in the 100 m (mean ± SD time: 51.95 ± 0.75 s) and the 200 m (mean ± SD time: 113.85 ± 2.67 s). For the 100 m events, the maximal relative load showed strong correlation with performance (r = 0.63) whereas trivial correlation was observed for the 200 m events (r = 0.12). SR on the 100 m and the 200 m also showed very strong association with rL0 (r = 0.83) and a strong association with V0 (r = 0.68) respectively.

Conclusion

The relationships between L-V variables and race variables depend on the distance of the event. However, L-V variables seem to be less related to SR and SL evolutions for the 100 m than in the 200 m event. Moreover, L-V profiles tend to be more related to the 100 m than 200 m freestyle performance. L-V profile should be interpreted taking into consideration the specific physiological and biomechanical constraints of the main events of the swimmer.

Reliability of a semi-tethered front crawl sprint performance test in adolescent swimmers

This study aimed to evaluate the test-retest reliability of a sprint performance test with semi-tethered front crawl swimming to indirectly assess the current potential to perform at maximal anaerobic effort in adolescent swimmers. Eight adolescent swimmers participated in this study (gender: females (n = 4) aged 13.0 ± 0.8 years, body height 1.6 ± 0.0 m, body mass 50.1 ± 4.5 kg; and males (n = 4) aged 13.3 ± 1.3 years, body height 1.7 ± 0.1 m, body mass 59.0 ± 8.2 kg. The testing protocol consisted of two trials of 25 m semi-tethered front crawl swimming with maximal effort and with 1 kg resisted isotonic load. Velocity data were recorded automatically by the 1080 Sprint device for 15 m (between 3 m and 18 m). The Fast Fourier Transform algorithm filtered raw instantaneous swimming velocity data in distance (time) function. A third-degree polynomial was used to extract the individual velocity profile, from which the following variables were chosen for test-retest reliability and the assessment of sprint performance: ttrial15, vmax, vmin, tvto max, tvat max, Dto vmax, Dat vmax, fatigue index. Parameters such as vmax, vmin, and ttrial15 were estimated from swimming velocity profiles and considered as reliable. The CV showed low variance <5%; while ICC2,1 demonstrated respectively good (ICC2,1: 0.88), very good (ICC2,1: 0.95), and excellent (ICC2,1: 0.98) rate of relative reliability; and the Bland-Altman index revealed an acceptable agreement (LoA ≤5%) between two measurements. The sprint performance test based on semi-tethered front crawl swimming confirmed that ttrial15, vmax, and vmin were reliable variables to indirectly indicate a potential to perform the maximal anaerobic effort among adolescent swimmers. The evaluation of the swimming velocity profiles allows coaches to monitor the adaptive changes of performance during the training process.

Reliability of the active drag assessment using an isotonic resisted sprint protocol in human swimming

The purpose of the presents study was to investigate the reliability of the active drag (D_a) assessment using the velocity perturbation method (VPM) with different external resisted forces. Eight male and eight female swimmers performed 25 m sprints with five isotonic loads (1–2–3–4–5 kg for females; 1–3–5–7–9 kg for males), which were repeated twice on different days. The mean velocity and semi-tethered force were computed for each condition, and the free-swimming maximum velocity was estimated with load-velocity profiling. From the obtained variables, D_a at the maximum free-swimming condition was calculated using VPM. Absolute and typical errors and the intra-class correlation (ICC) were calculated to assess test–retest reliability. 95% confidence interval (95% CI) lower bound of ICC was larger than 0.75 in 3, 4 (females only) and 5 kg trials in both sexes (corresponding to 37–60 N additional resistance; all p < 0.001), which also showed small absolute and relative typical errors (≤ 2.7 N and ≤ 4.4%). In both sexes, 1 kg load trial (16–17 N additional resistance) showed the lowest reliability (95% CI of ICC; − 0.25–0.83 in males and 0.07–0.94 in females). These results suggested that a tethered force of 37–60 N should be used to assess D_a using VPM.

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.