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Updated: Nov 8, 2021

I just need to get over the swim ‘I just need to get through the swim, after that it’ll be all good.’ As a swim coach I hear this all too often from beginner and experienced triathletes. Being the first of three disciplines the swim is setting your race up, more so if you are trying to enjoy the rest of the race! Athletes that don’t put enough importance or thought into their swim training are not doing themselves justice on race day. They exit the swim flustered with no composure, stumbling through transition to find their bikes adding seconds, if not minutes to their race time. Yes they’ve survived the swim, but by not following a structured endurance swim program they’ve over extended themselves and burnt valuable matches that they’ll need later in the race.

I’ve spent a lot of this season spectating from T1, the best racers are the ones looking the most relaxed when they come out of the water. These athletes are experienced and know how to pace their swim, managing their effort through the whole distance. They come out of the swim and fly through T1 in under 60 seconds. They’ve done this by developing pacing skills in training and simulating the endurance required for race day. T1 is so much easier when you’re not emptying the sea from your lungs.

'The most important technical thing about triathlon swimming is the ratio between threshold speed (CSS) and your maximum speed’ Alister Brownlee, Swim Bike Run: Our Triathlon Story, July 1, 2014 Alister is referring to the fact that triathlon isn’t about who can swim the fastest 100m but who can pace themselves the fastest over a longer distance, be it 750m, 1,500m to 3,800m. It’s like Usain Bolt vs Mo Farah. It’s all about pacing. Usain Bolt vs Mo Farah, the theory behind pacing Why can’t the Olympic 100m champ beat the Olympic 10,000m champ or visa versa? The answer is easy to guess over their respective distances, but what would happen somewhere in the middle? They are both super fit and breaking records, but who is faster?! According to scientific research the distance where this race becomes competitive is 492 metres. For Bolt, it’s whether he can withstand the fatigue of going three times further than his normal race distance. For Farah, it’s whether his top speed is fast enough to pressurise Bolt into fatigue. Farah and Bolt are training and pushing the limits on different parts of bodies energy systems and capacity. Short distance is all about explosive power and fast energy, the longer distance is all about how well you are managing your energy level to perform for the entire race. The theory behind this is the ability to exercise two different forms of energy, aerobic or anaerobic, and how they support our different exercise goals. The aerobic (Farah) uses energy from oxygen and is technically unlimited, anaerobic (Bolt) uses energy stored within the muscles is very limited. For endurance swimmers and triathletes, swim training needs to focused on building aerobic fitness for swimming. As you are using different muscle groups compared to running and cycling natural fitness levels don’t directly translate into swimming. We want to train like Mo but in the pool, developing both sources of energy systems with a focus on pacing and aerobic ability. This is done by training around our threshold swimming pace, known as Critical Swim Speed (CSS). A well structured training program will teach you how to pace yourself on race day. It will prepare you physically with the ability to swim faster and more efficient, as well as emotionally, the ability to pace and handle the pressure of race day. The pay-off is not always a faster time, although it’s often an outcome, but by pacing the swim you will retain more energy for the bike and run portions of the race. Tame the inner sprinter with a structured program based on threshold pace A structured swimming program for triathletes should contain 3 key elements year round to become an efficient swimmer: 1.Technique 2. Specific swimming fitness and pacing skills 3. Open water skills Whilst for this article I will focus on pacing skills, technique and open water skills are equally as important. Critical Swim Speed (CSS) was researched during early 90’s, providing an understanding of the bodies response to different swim intensities and developed a simple measure of aerobic capacity whilst swimming. CSS considers an athletes anaerobic and aerobic swimming ability using a 400m and 200m time trail, this speed closely equates to an athletes average pace over 1,500m. Swim Smooth has taken this concept to another level and built their weekly training plans around the Critical Swim Speed (CSS) of an athlete, similar to how cycling plans are developed around an athletes threshold power (FTP) or heart rate. CSS pace training can be used different ways for improving various elements of your swimming fitness, all applicable to racing. In our squad we used a mix for sessions built around CSS pacing, using the Finis Tempo Trainers Pro to help swimmers maintain their pacing. Steady/aerobic endurance : longer reps, paced at CSS + 8 to 12 sec/100m, The target of an endurance session is to build fatigue resistance and basic fitness, improving your aerobic conditioning. Additionally it helps to build mental skills for prolonged distance and pacing, giving you the confidence to swim long. Red Mist: longer reps with short rest, paced at CSS + 3 to 6 sec/100m Have you ever seen a 'red' when swimming? This session is all about challenging athletes both mentally and physically to deal with the pressure experienced during a race. It is a simulation of Ironman race conditions where a solid pace is maintained over a long distance, often with very little proper warm-up. It is a hard endurance session that will tap into a variety of energy systems from endurance to threshold pace. Threshold/CSS: mix of 100m to 400m, paced CSS ±2 sec/100m Challenging sets at threshold pace to develop swimmer's ability to sustain a strong pace over distance. It is also developing fatigue resistance, but at the “uncomfortably comfortable” intensity. This training results the muscle fibres becoming more conditioned to fatigue and therefore they tire less easily at this higher speed or intensity. VO2max: CSS – 4 to 6 sec/100m & Sprint: CSS -8 sec/100m and faster These sets are hard intensity and improve fatigue resistance at higher intensities, generally swum with shorter reps. These sessions are focusing on developing swimmers ability to cope with surges in pace during the race. These kind of intervals are good to combine with pool based open water session where the sprints are used to practice tactics for the race. For me info about the specific sessions you can find from Swim Smooth homepage: What now? Why don't you take a little challenge for the next 10 weeks. Test your CSS to understand your current fitness level, be consistent with your training and add at least one of the CSS training sessions to your plan each week. Depending on your fitness level you can see improvement from around 2.59% up to 13.62%. Calculating your CSS is done by performing 400m and 200m time trials with proper a warm up and easy swim in between. Details of the test and calculations can be found here: To help manage pacing in the pool we use The Finis Tempo Trainer, used correctly it can provide realtime feedback within millisecond accuracy. The best part is that it only costs a fraction of a sports watch. This is one of Swim Smooths favourite tools, to find out more visit Don’t just survive the swim, paced it and enjoy it!


1. ‘’Prediction and Quantification of Individual Athletic Performance’’, Duncan A.J. Blythe, Franz J. Király, 13 May 2015

2. “Critical Speed and Training Intensities for Swimming, Enid M.Ginn PhD, 1993, “A simple method for determining critical speed as swimming fatigue threshold competitive swimming” International Journal of Sports Medicine, 13, 367-371. Wakayoshi et al. ,1992

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