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

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.

Relationship between Maximum Force-Velocity Exertion and Swimming Performances among Four Strokes over Medium and Short Distances: The Stronger on Dry Land, the Faster in Water?

Evaluating force-velocity characteristics on dry-land is of the utmost importance in swimming, because higher levels of these bio-motor abilities positively affect in-water performance. However, the wide range of possible technical specializations presents an opportunity for a more categorized approach that has yet to be seized. Therefore, the aim of this study was to identify feasible differences in maximum force-velocity exertion based on swimmers' stroke and distance specialization. To this scope, 96 young male swimmers competing at the regional level were divided into 12 groups, one for each stroke (butterfly, backstroke, breaststroke, and front crawl) and distance (50 m, 100 m, and 200 m). They performed two single pull-up tests, 5-min before and after competing in a federal swimming race. We assessed force (N) and velocity (m/s) exertion via linear encoder. There were no significant differences between pre-post maximum force-velocity exertions, despite the decreasing trend. Force-parameters highly correlated with each other and with the swimming performance time. Moreover, both force (t = -3.60, p < 0.001) and velocity (t = -3.90, p < 0.001) were significant predictors of swimming race time. Sprinters (both 50 m and 100 m) of all strokes could exert significantly higher force-velocity compared to 200 m swimmers (e.g., 0.96 ± 0.06 m/s performed by sprinters vs. 0.66 ± 0.03 m/s performed by 200 m swimmers). Moreover, breaststroke sprinters presented significantly lower force-velocity compared to sprinters specialized in the other strokes (e.g., 1047.83 ± 61.33 N performed by breaststroke sprinters vs. 1263.62 ± 161.23 N performed by butterfly sprinters). This study could provide the foundation for future research regarding the role of stroke and distance specializations in modeling swimmers' force-velocity abilities, thus influencing paramount elements for specific training and improvement towards competitions.

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.