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More Information on High Intensity Swimming Training

This interview is with Dr. Nikolai Baastrup Nordsborg. Dr. Nordsborg has done extensive research in swimmers, particularly with high intensity swimming training adaptations. Here is the complete article which we discussed below.

1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).

I used to swim from age-group to junior level. I later obtained a one year competitive swim-coach education followed by five years at university studying exercise & sports science. During this period I also coached age-group and junior swimmers and was affiliated with the national Danish swimming federation.

In my professional career I obtained my Ph.D. related to muscle fatigue in 2005 and now hold a position as associate professor in exercise and sport science. One branch of my research activities is related to swimming.

2. You recently published an article on high intensity swimming training compared to traditional training. First, what does the past research suggest about these forms of training?

In the past, only few studies have attempted to systematically interfere with training intensity and volume in swimming. I think one of the most interesting studies is that of David Costill from 1991 ( in which it is demonstrated that a dramatic increase of training volume for XX weeks did not improve collegiate male swimmers endurance – but actually compromised their sprinting ability.  More recently a well conducted study of 9-11 years old children demonstrated that five weeks of high intensity swimming training vs. high-volume training resulted in performance after the high-intensity period ( Additionally, a four week intervention also demonstrated equal effects of high-volume and high-intensity training in competitive swimmers (

In recent years, high-intensity training has received a lot of attention in untrained populations as well as in runners, cyclists and football players. The majority of studies demonstrate high-intensity low-volume to be a more efficient paradigm in order to improve performance.

Based on these observations, it appeared contradictory that swimmers (often competing < 130 s) should be doing a type of training with very high volume and not so much high intensity swimming training. Some of the arguments for the high volume was: The volume is important when the duration is longer than 6-8 weeks and the response will be different in a group of high-level swimmers.

3. What did your study look at?

In our study, one group of swimmers halved their volume and more than doubled the high-intensity work whereas the other group maintained their normal training for 12 weeks. The intense training was completed as 6-10×10-30 s maximal effort interspersed by 2–4 minutes of rest. All testing was done in freestyle whereas in training all strokes were allowed.

Before doing the study we wondered if the protocol would either benefit the high intensity swimming training group – or possibly reduce performance due to the lower total training volume.

4. What were the results of your study?

We found that the intervention did not affect the swimmers despite the training being very different (

5. How did you choose your swimming training methods and what do you think would have happened if the swimmers did more repetitions High Intensity Swimming Trainingwith a shorter rest (20×50 @:20 rest) or less repetitions on a longer rest (4×50 @5:00rest)?

The high intensity swimming training intervals were designed to allow maximal effort at every swim. If the resting is reduced then the recovery between sets will also be reduced and the metabolism will be more aerobic along with a reduced type 2 fiber type recruitment. Thus, it will resemble classical “aerobic high-intensity training”. There are studies in cyclist showing that performance can be improved by various forms of high-intensity training ( However, these athletes are not as used to high-intensity training as swimmers so they may be more responsive to inclusion of IT. If the recovery period is increased the training response would potentially be the same but there is really no reason to prolong the period between repetitions.

6. Do you think the results would be different if you had older, younger or untrained swimmers?

We just completed a swim training study in women around 40-60 yrs. One group did 6-10 x 30s separated by 2 min and another swam continuously for 1 h. Adaptations were similar with high- and moderate-intensity training, despite markedly less total time spent and distance covered in the high intensity swimming training group ( So this corresponds to the findings from the group of elite swimmers. As previously stated, the response also seem to be the same in children.

7. The low volume and high volume debate will always occur in swimming. What do you think is best training approach?

I think you need to swim a lot in order to improve your movement efficiency in water. But, I do not think that it is necessary to do 4-5 hrs of swimming hard aerobic intervals every day at the age of 10-16 in order to be a high level swimmer. I actually think that this type of training results in the loss of excellent swimmers that cannot find the motivation for the long training sessions. So an optimal training strategy may be to do a lot of swimming, but in a fun and motivating way with less focus on the physiological outcome. When that is said, I think it is of extreme importance to include high intensity swimming training sessions like the 8 x 50 m all-out separated by 2-3 minutes of rest 2-4 times per week. To put it short: Improve your technique; do sprint intervals and top off with a few hard aerobic workouts and a lot of fun.

8. Do you think one training approach is best for each athlete?

Yes, but this has not been scientifically proven. From personal experience, I have seen sprinters who have a really hard time doing the very long though aerobic sets and at the same time does not appear to benefit from them.

9. What other studies could clarify ideal training methods for swimmers?

There a still a number of studies to do. The difficult, but important, studies will be the ones addressing yearly training cycles. How is the optimal yearly interaction between high intensity swimming training (sprint and / or aerobic) and heavy resistance training and tapering? And how can ergogenic aids influence the training outcome? Is it possible to take a break for some years and then return to high-level swimming (some have tried with different degrees of success).

10. What makes your research different from others?

I am in an environment were applied exercise physiology is combined with molecular physiology. We strive to understand at a molecular level how one training paradigm differs from another. Thus, our conclusions are more broadly applicable.

11. Which teachers have most influenced your research?

During my Ph.D. studies I had Prof. Jens Bangsbo as a supervisor and he is one of the pioneers in scientific research related to high-intensity training. Jens have definetly influenced how I think about training and research in general.

12. What research or projects are you currently working on or should we look from you in the future?

We continue the work with high intensity swimming training vs high volume training in swimming. Hopefully we will have two new papers out this year, dealing will the mental stress of swimmers doing high-intensity training and muscular adaptations of arm and leg muscle. Additionally, we are currently looking into the importance of hypoxic exposure for swimmers performance. Stay tuned…

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