The 50 m freestyle swimming race is one of the fastest events in competitive swimming, relying heavily on an athlete’s explosive force and swimming technique (1, 38). In fact, a classical study by Hawley et al. (2) demonstrated that upper- and lower-limb muscle power, as assessed during Wingate Anaerobic Tests, were significantly correlated with 50 m swimming speed (r = 0.63 and 0.76, respectively). More recent data from Loturco et al. (3) support this idea, as they found strong correlations (r = −0.72 and −0.76, respectively) between the rate of force development and impulse during tethered swimming and 50 m freestyle swimming time. These findings highlight the importance of both muscle power and swimming technique in achieving optimal performance in the 50 m freestyle swimming race.

Explosive force is a key component of human performance that can be developed through strength training (4). However, there are also strategies to acutely enhance muscle power that can be used in conjunction with strength training. One such strategy is post-activation performance enhancement (PAPE) (5–7). PAPE has been extensively studied in the past two decades, particularly in relation to land-based activities like jumping (8, 9) and sprinting (10, 11). For these types of activities, it is well-established that performing pre-activation activities involving heavy weightlifting a few minutes prior to explosive muscle actions leads to improved performance (10–13). The magnitude of this effect can be influenced by several factors, including strength, sex, level of training, and the protocol of the pre-activation activity (including the amount of resistance, number of sets, and time between the pre-activation and the potentiated action) (7, 14). Despite being consistently investigated in land-based activities, the occurrence of PAPE in swimming is still being studied and has produced conflicting results (15, 16).

To the best of our knowledge, the study by Kilduff and colleagues (17) was the first to investigate the effects of PAPE in swimmers. They reported that performing one set of heavy-weight squats approximately 8 min prior to a 15 m swim start led to improvements in peak vertical and horizontal forces applied to the block, but no improvements in 15 m time compared to traditional warm-up. Other studies have also investigated the effectiveness of different pre-activation protocols in enhancing start and swimming performance. These protocols have involved dryland traditional resistance exercise (for either upper and lower limbs or a combination of both) (18–25), dryland lower-limb flywheel exercise (19), combined lower- and upper-limb flywheel exercise (23), tethered swimming (26, 27), and parachute-resisted swimming (28).

While the studies mentioned have contributed to understanding swimming PAPE, most of them utilized methods that are not practical for everyday training or competitions due the sizes, weights, and ease of transportation of the equipment involved or the complexity of the logistics of the pre-activation protocols. To our knowledge, only Barbosa et al. (28) investigated the effects of a parachute-resisted pre-activation protocol on swimming propulsive force but, although they did assess swimming performance, time to completion of simulated races was not investigated. Thus, there is a gap in the literature regarding ecologically valid in-water pre-activation methods that can enhance swimming performance using accessible equipment and infrastructure.

Schnitzler et al. (29) showed that parachute-resisted swimming results in greater drag force and, consequently, greater propulsive force required to sustain the same swimming velocity. Additionally, swimming with hand paddles was shown to increase average stroke force and impulse during tethered swimming (39). Considering that responsiveness to PAPE depends on the amount of resistance applied during the pre-activation exercise (7), parachute-resisted swimming using large hand-paddles appears to be a good, ecologically valid, and practical strategy to induce such phenomenon in sprint swimmers. Therefore, we aimed to determine warming up with parachute-resisted sprints with large hand-paddles improves 50 m freestyle swimming performance. We hypothesized that such warm-up strategy would improve performance in a 50 m swim by increasing stroke frequency.

The reliability of the measurements was high, with intraclass correlation coefficients and confidence intervals of 0.93 (0.77–0.98), 0.91 (0.70–0.98), 0.94 (0.80–0.98), 0.91 (0.71–0.98), and 0.94 (0.78–0.98) for 25 m and 50 m times, stroke frequency, stroke length, and stroke propulsive time, respectively. Figure 1 displays the results for swimming performance. The 25 m swimming time did not differ significantly (p = 0.28) between the CON (12.6 ± 0.8 s) and EXP (12.5 ± 0.8 s) conditions (Figure 1A), and the same was true for the 50 m swimming time (CON: 26.8 ± 1.6 s; EXP: 26.7 ± 1.7 s; p = 0.54) (Figure 1B). Individual analyses using the SWC method showed that two subjects had decreased and one had increased their 25 m swimming times (Figure 1C), whereas one subject decreased and two increased their 50 m swimming times (Figure 1D).

Figure 2 presents the swimming technique data, which showed that none of the assessed kinematic parameters were significantly affected by the different warm-up conditions. There were no significant differences in stroke frequency between the CON (55.4 ± 5.3 cycles.min⁻¹) and EXP (56.3 ± 5.2 cycles.min⁻¹) conditions (p = 0.32). Similarly, stroke length was not significantly different between the CON (2.04 ± 0.21 m.cycle⁻¹) and EXP (2.02 ± 0.22 m.cycle⁻¹) conditions (p = 0.33). Additionally, stroke propulsive time was not significantly different between the CON (0.62 ± 0.07 s) and EXP (0.61 ± 0.06 s) conditions (p = 0.06).

The main goal of this study was to examine whether using large hand-paddles and performing parachute-resisted sprints as a warm-up could lead to improvements in swimming performance during a subsequent 50 m freestyle race, as well as changes in swimming technique. The hypothesis was that the additional drag and propulsion from these warm-up techniques would result in a performance enhancement. However, the results showed that there were no significant differences in performance between the experimental (EXP) warm-up and the traditional (CON) warm-up. Additionally, there were no observable differences in swimming technique between the two warm-up routines.

PAPE is most relevant for powerful actions, such as dryland sprints, jumps and, in the case of the present study, 50 m freestyle swim races, which are the most powerful swimming events in competitive swimming (1, 2). It can be used as a pre-competitive strategy to enhance performance during races, as well as during training sessions to improve their quality, which is commonly referred to as contrast training (32, 33).

Several factors have been suggested to influence responsiveness to PAPE, and it seems that training status plays a role in modulating the response to pre-activation activities. Studies indicate that trained and/or stronger individuals tend to respond better to dryland PAPE compared to their untrained or weaker counterparts (7, 14). For the present study, collegiate swimmers who could complete 50-m freestyle races in under 28 s were recruited. Although these times are not at the elite level, this exclusion criterion was implemented to ensure that all participants were experienced and capable of performing above the amateur level. As a result, the sample was relatively homogeneous, and more importantly, familiar with high-speed swimming training. This may have reduced the responsiveness bias associated with training status that is commonly observed in PAPE studies (7, 8).

The present study did not observe any PAPE response for the dependent variables investigated following the EXP warm-up. As far as we know, this is only the second study to investigate responsiveness to PAPE following parachute-resisted sprint swimming. Barbosa et al. (28) reported that a different configuration of parachute-resisted swimming (8 × 12.5 m sprints) resulted in compromised peak force and impulse but not the rate of force development during maximal tethered swimming. The authors discussed that the pre-activation protocol used in their study might have imposed excessive stress on the swimmers, resulting in a fatigued state during performance assessments. With this in mind, we have adjusted the EXP protocol of our study by reducing the number of sprints to modulate the stress imposed and allow for optimal recovery. Our findings suggest that the investigated warm-up protocol was not stressful enough to compromise performance, but it also did not appear to have been stressful enough to elicit the physiological mechanisms underpinning PAPE.

Several other studies investigating PAPE for swimmers have suggested using dryland exercises such as repeated jumps, squats, and pull-ups in the warm-up protocol (18–25). However, a frequent observation of these studies is that, although successful in improving swimming start performance (15, 23–25), the potentiating effect induced by dryland exercise does not appear to be transferred to swimming (20, 21, 23, 24). This often leads to improved start performance but no impact on overall race performance, which is mainly determined by swimming, as it accounts for the majority of the race time.

Our study’s results are similar to those of Abbes et al. (20), who found no changes in 50 m swimming performance for regional-level swimmers after a warm-up consisting of three 10 s maximal tethered swimming sprints. However, Hancock et al. (26) observed improvements in 100 m freestyle swimming performance in collegiate swimmers following four 10 m maximal tethered swimming sprints. Nonetheless, it is important to note that comparisons between studies should be made carefully, as tethered swimming differs from parachute-resisted swimming in terms of load control during sprints. Given our objective of proposing an ecologically valid warm-up strategy that could be used in everyday training sessions and competitive settings, tethered swimming was not a practical option.

The lack of difference in swimming performance and technique following the EXP warm-up in our study may be attributed to its similarity with the CON warm-up. The only variation between the two warm-ups was the intensity of the four 10 s sprints at the end of the routine. Since high-intensity efforts are usually included in sprinters’ warm-up routines, we chose to increase the stress imposed to muscles by adding a parachute and large hand-paddles to further increase drag force. Schniztler et al. (29) showed that using the same parachute led to a 12.6% increase in peak propulsive force and a 9.8% increase in propulsive impulse during constant-speed tethered swimming. In our study, we did not quantify the additional resistance imposed by the parachute, which can be considered a limitation. This quantification could have been used to compare the amount of imposed stress between the two warm-up routines. However, we speculate that a significant amount of stress was already provided during the sprint phase of the CON warm-up routine and that the additional drag imposed by parachute-resisted sprinting during the EXP warm-up may have been insufficient to enhance swimming technique and performance further.

It is generally agreed that using heavy loads, around 80%–90% of the one-repetition maximum (1RM), is the most effective way to induce PAPE during dryland exercises (7), with studies comparing light and heavy pre-activation protocols having shown that the former can produce greater improvements in jump height and repeated sprint ability (34, 35). While we acknowledge these findings, we do not think it would be appropriate to compare a heavy-load warm-up protocol, such as parachute swimming, with a warm-up routine that does not include high-intensity efforts like short-distance sprints, as these sprints are a common element of traditional warm-up protocols for sprint swimmers. Thus, we suggest that future studies should explore different experimental warm-ups to find the optimal pre-activation load that can trigger PAPE without causing performance-reducing fatigue.

The recovery interval between the pre-activation warm-up routine and performance assessment can have a significant impact on responsiveness to PAPE. In our study, we used a 6 min recovery interval, which has been shown to allow for fatigue recovery while also benefiting from the relatively short-lasting mechanisms underpinning PAPE (5, 7, 36). However, the ideal recovery interval for PAPE is highly variable and controversial, even among individuals with the same training background (37). It is possible that some subjects in our study may have responded to the EXP warm-up protocol, but the 6-minute recovery window was not optimal for them. One possible solution is to use a self-selected recovery interval, where individuals are allowed to choose the interval between the pre-activation and performance assessment by filling out a readiness scale. A recent study by Carmo et al. (36) demonstrated that this approach resulted in greater responsiveness to PAPE in trained individuals. This should be considered when designing future studies investigating PAPE.

The results of our study suggest that adding a swimming parachute and large hand-paddles to warm-up routines may not enhance 50 m freestyle swimming performance compared to traditional warm-ups. Coaches and practitioners are encouraged to experiment with different loads during warm-up routines to determine whether parachute-resisted sprints can improve their athletes’ swimming performance. It is also important to investigate the optimal recovery time between warm-up routines and swimming efforts. By doing so, coaches and practitioners can determine whether traditional warm-ups are already optimal for their athletes or if there are better warm-up routines to improve swimming performance.