Science of Performance: Strength Training and Swimming Performance

Photo Courtesy: David Farr

Commentary by G. John Mullen

SANTA CLARA, California, September 17. IN my last post, I reviewed some information regarding dryland training. Overall, dryland/strength training is a poorly research field, leaving many gaps in the literature. However, reviewing the complete body of literature, using the highest quality of research, and not lumping all dryland together is essential for evaluation and recommendation. Here is a review of more studies on strength training and swimming which I can find. Unfortunately, in every literature review, finding each article on the subject is impossible. If any readers have research articles, please post them in the comments:

Strass 1986:

Strass (1986) found a 7.3% improvement in 50m freestyle with the intervention group after a heavy, explosive strength training regimen (three repetitions per three sets at 90% resistance of one-repetition maximum (1RM), two repetitions per two sets at 95% of 1RM, one repetition at 100% of 1RM and one repetition attempted at 100% of 1RM+1kg) of the elbow extensors for four sessions per week across 6 weeks.

Like other studies mentioned, this study had some flaws. Strass (1986) did not supply any control group data from pre- or post-tests in numbers. He did, however, report a small, but possibly significant age difference between the groups (mean age 16.6 years in the intervention group and mean age 17.8 years in the control group, not reporting whether the difference was significant). Furthermore, the measurements of isometric force may limit the data interpretation, as swimming is a dynamic exercise and isometric tests may not always be an accurate measure of dynamic muscular capacity (Wilson 1996).

Overall, this high-intensity low volume (only one exercise!) resistance training approach may improve 50-m performance.

Girold 2007:

Girold (2007) compared strength training (S), resisted swimming (RS), and a control group (C; biking). This trial was 12-weeks and the training was performed biweekly. The resistance training specifically was explosive dryland strength training (six different exercises with three times six repetitions of explosive-type strength training at 80–90% of 1RM).

Improvements in strength training were supported by Girold (2007) finding improvement in the 50m freestyle after 12 weeks of biweekly sessions of This trial compared strength training (S), resisted swimming (RS), and a control group (C; biking). The strength and resisted swimming groups had significant improvement in a 50-meter time trial. The strength group improved 2.8%, resisted swimming 2.3% and control 0.9%. There was no significant difference between the improvement of S and RS. Isometric strength of the elbow flexors was significantly increased in S and RS, but not C.

Now, this study appears positive for resistance training, but the swimmers were intermediate in speed, and the type of control training may have inhibited performance (causing overtraining). Moreover, only a 50-m was assessed, making gross assumptions of other events and distances unwarranted.

Both studies also found improvements within the respective strength parameters, and concluded that their strength-training interventions were successful. However, data from small study groups are scientifically fragile compared with larger study groups, and like many of the other studies included in this review the findings of these studies may be limited by the low number of subjects (on average 4.5 and 7).

Girold 2012:

Girold (2012) more recently looked at twenty-four national-level competitive swimmers (M=12, F=12; ~21.8 years; 27.8 +- 1.8 seconds top 50 m time) who averaged 20 hours of swim training per week. These swimmers were split into dryland (S), electrical stimulation (ES), and control (C) groups. The strength sessions were 15 minutes long, preceded by a 10-minute warm-up which was performed 3 times per week before swimming. The program included 3 sets of 3 exercises with 2 minutes rest between each set. Each set consisted of a maximum of 6 repetitions of pull-ups and draws with pulleys. “The exercises included pull-ups and draws with pulleys. To perform the exercises under the most specific conditions, they were performed with the hand in a pronation grip and the distance between the 2 hands set at shoulder width. The swimmers were instructed to pull on the bar until it reached the level of the chest when performing pull-ups and first draw exercises. For the second draw exercise, swimmers were instructed to pull on the handle until it reached the level of the hips. For pull-ups, the swimmers’ own body weight was used as resistance. For the draw exercises, the swimmers were seated on a bench with their legs locked under a bar to avoid any movement of the lower limbs. The intensity of the training varied between 80 and 90% of the maximal load for the draw exercises in relation to the 1RM tests performed before the start of the study. For each repetition, the swimmers were instructed to perform the concentric phase of the movement as fast as possible, maintain a 3-second isometric contraction and return to the initial position by slowing the movement (eccentric phase). The exercise rate was approximately 1 movement every 6 seconds (Girold 2012).”

The ES program performed the same 10-minute warm-up as the S group followed by electrical stimulation to the latissimi dorsi.

Swimming velocity significantly improved in the 50-m freestyle at the end of training in the S and ES group (2.0% and 1.7% improvement, respectively). Even four weeks after the study, significant improvement existed, but the results were not significant from one another. After 4 weeks stroke length was significantly increased in the S, but not the ES or C group. Peak torque significantly increased at moderate and fast speeds for the S and ES group. ES also improved in strength for isometric and eccentric contractions. No differences were noted between men and women.

Again, these results seem quite positive for resistance training, but keep in mind; it only looked at a 50-m velocity, no longer distances. Moreover, the volume of resistance training was quite low. Also, the training only lasted 4 weeks, with most of the improvements persisting after four weeks. This suggests, cycling through resistance training may be beneficial. For ES, it is likely this low volume may have increased strength, causing performance improvements, more studies on ES is needed.

Aspenes 2009:

Aspenes (2009) compared combined intervention of strength (~two weekly sessions of an explosive pull-down strength training regimen of five repetitions with maximal load relative to the number of repetitions over three sets) and endurance training (two weekly sessions of 4 times 4 minutes of high-intensity interval training), with a control group that only performed regular swimming training. The intervention was eleven weeks in total. Mean age in the intervention group was 17.5 years (n = 11, 6 males), and in the control group 15.9 years (n = 9, 2 males).

The intervention group improved land strength, tethered swimming force and 400m freestyle performance more than the control group.

Although (Aspenes 2009) partly agrees with the aforementioned trials, indicating that dryland strength training may benefit swimming performance, a crossover effect from the endurance intervention may potentially have influenced the findings (Aspenes 2009). Aspenes (2009) may also be limited by the lack of a randomization design, like many other studies. In addition, the intervention group and the control group were not similar with respect to sex (7 of 9 subjects were female in the control group, 5 of 11 subjects were female in the intervention group).

Trappe 1994:

Although the previous studies are positive, opposing work does exist.

A study from Trappe and Pearson (1994) compared weight-assisted training (three sets of dips and pull-ups with no assistance until volitional fatigue, 13.6 kg assistance and 22.7 kg assistance, respectively) to dryland strength training (six exercises with three sets of 8–12 repetitions with progressive maximal load until exhaustion) in addition to common swim practice, and found no differences in 50 yard or 400 yard swimming performance between the groups.

The possible effects were inadequately controlled, as the strength training intervention was carried out during the first 6 weeks of a 12-week observation, and performance tested in weeks 4 and 12 in both groups, which makes it challenging to draw inferences. Nonetheless, the results suggest higher volume dryland is not beneficial for swimming sprints or endurance events.

Sadowski 2012:

Sadowski (2012) randomly assigned twenty six male swimmers (mean age 14) to either a swimming or dryland power training (experimental) or swimming only (control) group. Then the subjects were tested with hydroisokinetic ergometer. The swimming training consisted of six weeks of doubles every day except Sunday and one training session on Saturday. All subjects swam 273.50 km during the whole experiment. The power training consisted of circuit training, of 6 sets of 50 seconds of work and 10 seconds of rest on the ergometer (Sadowski 2012). The experimental group had significant improvements in tethered swimming force, but both groups noted non-statistically differences in 25-m performance.

These results suggest the common circuit training may not be beneficial for age-group swimmers for enhancing sprint swimming performance.

Conclusion

The reviewed studies of dryland strength training on swimming performance indicate that there may be positive associations between maximal dryland strength training and swimming performance. However, due to a low number of eligible studies, lack of information, variety between the interventions, subject characteristics and effects, low numbers of study participants, combined intervention design and lack of randomized study designs, further randomized controlled trials (RCTs) on the effects of dryland strength training should be carried out in competitive swimmers.

If any conclusions can be drawn it is the following:
1. High volume dry-land training combined with high-volume swimming unlikely enhancements performance.
2. High-intensity, low volume, short duration dryland training has the highest potential of improving sprint and endurance swimming performance.
3. There is a lack of research on this area, despite the common implementation of dryland.

The next installment will talk about other possible avenues for dryland training, as strength training is only one component. More on dryland, strength training, and team programming is available in Dryland for Swimmers.

References:

Girold S, Maurin D, Dugué B, Chatard JC, Millet G. Effects of dry-land vs. resisted- and assisted-sprint exercises on swimming sprint performances. J Strength Cond Res. 2007 May;21(2):599-605
Girold S, Jalab C, Bernard O, Carette P, Kemoun G, Dugué B. Dry-land strength training vs. electrical stimulation in sprint swimming performance. J Strength Cond Res. 2012 Feb;26(2):497-505.
Aspenes S, Kjendlie PL, Hoff J, et al. Combined strength and endurance training in competitive swimmers. J Sports Sci Med 2009 Sept; 8 (3): 357-65.
Trappe S, Pearson D. Effects of weight assisted dry-land strength training on swimming performance. J Strength Cond Res 1994 Nov; 8 (4): 209-13.
Strass D. Effects of maximal strength training on sprint performance of competitive swimmers. In: Ungerechts BE, Wilke K, Reischle K, editors. Vth International Symposium of Biomechanics and Medicine in Swimming; 1986 Jul 27-31. Bielefeld: Human Kinetics Books, 1986: 149-56
Sadowski J, Mastalerz A, Gromisz W, NiŸnikowski T. Effectiveness of the power dry-land training programmes in youth swimmers. J Hum Kinet. 2012 May;32:77-86. doi: 10.2478/v10078-012-0025-5. Epub 2012 May 30.

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Allen

9 years ago

Competitive swimming has been around many decades and almost all swimming programs at every level incorporate some form of dryland and/or strength training program, yet there’s still a lack of research in this area? Where’s the science in swimming?

Dan Smith

9 years ago

You need money to conduct good research…research into swimming is woefully underfunded. There may be strength training research out there but it may have been privately funded, which means the results are private. I agree there is a lack of research, but academic-research based on solid science is not done for free, or at low cost. If you look at the sample sizes presented above, the sample sizes are low for making any statements that support the hypotheses. If you do a quick exploratory data analysis on required statistical sample size, based on Tukey or any other excellent statistician, you’ll see these sample sizes are not in the range to predict much. More money = more studies.

G. John Mullen

9 years ago

Reply to Dan Smith

Dan Smith, great answer to Allen’s question. From my understanding, there is no system for obtaining grants for swimming related research in the United States. For a personal example, while in my Doctorate program, I proposed some swimming related research and searched for grant programs from the main organizations and governing bodies in the United States and found nothing (in 2009)! Therefore, a simple study of lung adaptations in various environments (aquatic and on land) would have cost me ~200 hours of time and ~$15,000, something I didn’t have in graduate school.

This lack of funding inhibits research, as it takes a lot of money and time for research. Most of the research on swimming is related to products in the United States, which is fine, but does create some conflict of interest. Most of the swimming literature is done in foreign countries (Portugal, France, etc.) where they have Masters and Doctorates in “coaching”, encouraging research of their main sports.

If the swimming society wants more research on swimming the members (coaches, swimmers, officials, etc.) must encourage change with the governing and educational bodies.

Allen

9 years ago

I’m amazed that the national organization, USA Swimming, hasn’t invested more into research to better understand swimming and, ultimately, help its swimmers succeed at international competition. It seems that much of the knowledge about swimming in the USA is still based on folklore and anecdotal evidence. I’m glad we at least have swimmingscience.net to separate swimming facts from fiction!

Dan Smith

9 years ago

I am not amazed. Love the sport and always have but in the 50+ years I’ve been involved and around it the pattern that “Once every four years” for national attention on swimming is the norm. While the brains are certainly there to set up the research, the funding needs to be there. And, the funding is not just in measuring equipment. You need to pay the people doing the research the going rate for their time when working on it…as well as support staff. And, the study (or several) need to be both cross-sectional (slice of time) but even better longitudinal (though time and a generation for example) as well as have enough swimmers participating that the results mean something in the scientific community and passes peer review. The one thing where studies could potentially garner some funding is if the studies were cast in “human performance” or “human performance and health), or “human growth, development and health”…that gets one in the ballpark (IMO), but still may not be enough to get the amount of funding needed. And, realize, funding is ephemeral…funding can come and go in a year, and the rug get yanked at any time by a funding agency, group, or individual. “crowd-funding” meaning a group of agencies and businesses could decide to fund, but the legal issues on results would have to be hammered out in advance, as someone like a sports drink company supporting it wants the data to improve their profits…so publication could be sensitive and future use of results could be sensitive at best. In research when people apply for funding the results are graded: “Wonderful!”, “Fantastic!” and the top rating “Worthy of Funding!”_—and even then it is not a guarantee and yes, there are politics involved too. Would love it if a large multi-year, multidisciplinary study was funded , but given other needs to society I am not holding my breath.

G. John Mullen

9 years ago

Reply to Dan Smith

Great comments, couldn’t agree more. Thanks Dan.