How often should you interval train for maximum fitness gains? Andrew Hamilton takes a look at some brand new research and comes up with surprising conclusions MORE
Tabata interval training for strength and endurance
Time-efficient strength and endurance workout
Article at a glance
We may be living in an increasingly wealthy world, but the demands of 21st-century living mean that many of us are increasingly time poor. But according to James Marshall, by adjusting volume and intensity, and monitoring the sequence of training exercises, athletes who have busy lives can still enhance their sporting performance with workouts of just 30 minutes duration
Here’s a question for you. If you could only spare 30 minutes a day for your training schedule, how could you best utilise that time? Would the recommendations be different for beginners (less than 6 months’ training) and for more experienced athletes (more than 2 years’ training)? And is it worth trying to combine strength and conditioning workouts, or does that dilute the training effect for both? This article will explain how to make the most of your time and give examples of workouts that you can do.
Measuring effective workouts
If you are an Olympic weightlifter or a marathon runner, you can be pretty sure about what energy system you will be using in your sport and training accordingly. But most people use more than one energy system to a greater or lesser degree in competition and in training. Academic research that looks at one energy system and an objective measure, such as maximum oxygen uptake (VO2max) can manipulate variables and find the best training method that improves that measure. However, research that looks at training different energy systems concurrently is more difficult, because defining the best measurement of performance is not always straightforward. This type of research is more limited (for example combining strength and endurance sessions) and the design of the study has to be looked at in detail before making conclusions from the data. However, it is this type of study that has most relevance for those coaches and athletes working in (most) sports where the athlete has to be quick, powerful and have the ability to repeat that throughout the match or rounds of a competition.
An alternative to combining different training types is to prioritise one area at a time then trying to combine two or three of these different areas into your weekly or monthly plan. Let’s start by looking at endurance; what’s the best way to improve it in 30 minutes? Should you just run, cycle or swim for 30 minutes continuously? This type of workout has its place, and beginners are encouraged to build up their level of fitness by progressing to this continuous steady state work. It’s also very useful for athletes in season who want to maintain their body composition by exercising submaximally and in a different format from their sport. However, if you are more experienced and you want to improve your performance then interval training will be the most efficient way of doing this. But what type of interval training is most effective?
One of the most popular interval methods is known commonly as ‘Tabata Intervals’ after the lead researcher in two 1990s Japanese studies about the effectiveness of short duration, high-intensity workouts(1,2).
The first study consisted of two training protocols using a cycle ergometer. The first protocol used a constant workload of 70% of VO2max for one hour, 5 days a week. After 6 weeks the VO2max had increased from 53ml/kg/min to 58ml/kg/min, but there was no significant change in anaerobic capacity.
The second protocol worked on high-intensity intervals of 20 seconds work, 10 seconds rest. The work rate was at 170% of VO2max and 7-8 sets were done each day for 5 days a week. In the second protocol VO2max increased by 7ml/kg/min (ie more than steady state) and anaerobic capacity improved by 28%. When you look at the total time spent in training for the two sets of subjects, the first protocol involved 30 hours training, while the second involved only 2 hours!
Tabata then compared this highly effective interval workout with a protocol using 4-5 repetitions of a 30-second workout at 200% of VO2max and 2-minute rest intervals. He looked at both the accumulated oxygen deficits of the two protocols and the peak oxygen uptakes during the last 10 seconds of each interval. It was clear that the 20:10 seconds work:rest ratio taxed the anaerobic and aerobic systems maximally. The advantage of 20:10 Tabata intervals is that they are very effective and do not take a long time at all. The disadvantage is that they are very hard work and it takes a highly motivated athlete to work at the high levels of intensity required!
Other studies have looked at different interval work:rest ratios and also how their subjects coped with the workloads. One study compared a work:rest ratio of 1:1.5 during 40 minutes of treadmill running with the work intervals being either 6 , 12 or 18 seconds(3). The work rate was at 120% of VO2max (easier than the Tabatas at 170%) and the rest was passive. The 12 and 18-second work intervals were more effective than the 6 seconds at inducing physiological strain measured by respiratory exchange and mean exercise intensity.
Another study looked at well-trained male runners performing six 4-minute intervals on a treadmill up a 5% incline, running at their chosen speed but trying to get the most work done(4). The runners either had 1, 2 or 4 minutes rest. They also did a test where they self-selected their own rest interval. Interestingly the average self-selection was 118 seconds, and while there was not much difference in performance between the three different rest intervals, more overall work was done with a 2-minute rest period. Maybe these experienced runners already knew what worked best for them and also knew how to push themselves accordingly.
Best work interval length
One way of measuring the length of your work intervals is to work on percentages of your maximal work time at full pace. A study on experienced cyclists showed that using intervals with a work interval length of 60% of their time to failure while cycling at their peak power output was the most effective at improving their 40km time trial performance(5). This required only 8 sets of work at a 1:2 work:rest ratio. The subjects performed this twice a week for 4 weeks, as well as their normal low-intensity workouts on other days. This shows that even a short intervention can make a difference if the work is of sufficient quality.
However, when beginning interval training, it may be better to use slightly shorter work intervals, and progress by increasing the work time. A recent study in Japan looked at running at 100% of VO2max and then working at 50% of VO2max during the recovery period(6). Work to rest intervals (in seconds) of 15:15, 30:15 and 60:15 were measured. Only five of the 12 subjects were able to complete the 60-second work trial, which produced blood lactate levels of 12.5mmol (high!). When measuring the percentage of VO2max that was used during the trial, the 15:15 protocol elicited significantly less than the other two, and the researchers concluded that a 2:1 work to rest ratio could be a good way to start (the same as the Tabata intervals).
So far we have looked at time effective ways for athletes who are trying to enhance their endurance capacity or their strength. If you need to do both, you can either concentrate on one aspect at a time, or you can try to do both at the same time by either alternating strength and endurance workouts (inter-session) or combine the two in the same workout (intra-session).
Concurrent training has been the subject of lots of recent research; some findings indicate that you can improve both strength and endurance at the same time, while others indicate that it impedes development of one or both.
Before looking at this research, it may be useful to briefly look at the theory as to why working on the two systems concurrently may be detrimental. A recent review of the literature looked at the effects of concurrent training on muscle protein synthesis(9). It appears to be the case that the proteins responsible for endurance metabolism antagonise muscle protein synthesis. The release of the proteins stimulated by endurance training interferes with the internal signalling systems that are necessary for muscle growth(10). In the short term, endurance training will reduce strength adaptation so overlapping strength and endurance sessions will prevent full recovery from the strength sessions. If full recovery is not allowed, then the athlete does not adapt and become stronger. If an adaptation window is provided, then the athlete can recover and become stronger.
Depending on your sport-specific training schedule, one to two sessions per week of endurance training will not interfere with your strength training. However, if your playing and training schedule is causing big demands on your endurance energy systems, then any additional endurance work will increase the likelihood of interference with muscle strength adaptations.
Primary goal of endurance – If your primary goal is to increase endurance, then combining endurance work with a circuit or explosive strength workout will help you according to two different studies. In the first study using students as subjects, the authors looked at intra-session concurrent training(11). They found better results as measured by a 4km running time trial for those subjects who did circuit training immediately after individualised endurance training in the same session than the opposite order or when each of the training programmes was performed separately. In the second study, runners replaced 19% of their running volume with explosive strength training(12). Compared with a control group who just ran, the concurrent trainers had greater improvement in maximal anaerobic capacity, 30m sprint speed, concentric and eccentric leg strength and also rate of force development – all of which are essential in most intermittent team sports. Clearly in both of these studies, combining some strength and endurance training did not adversely affect endurance capacity, but actually enhanced performance.
Primary goal of strength – What if strength is your primary goal, but you still need endurance? Studies have found that while endurance training improves endurance, and strength training improves strength and power, they have little affect on other parameters of fitness whereas concurrent training improves aspects of both(13,14). This includes measurements of body composition, lean mass, maximal force and 1-RM strength.
However, only one study has looked at team sports in season. Using experienced, well-trained professional rugby league players, the author periodised the training over a 19-week season(15). Using both strength and endurance sessions, the subjects did not lose any of their pre-season strength or power during the season, despite having a very heavy playing load. This is not the case in many other sports where there is generally a decline in fitness parameters over the course of the season. Interestingly the same study looked at college rugby league players over the course of their 29-week season following a similar programme and they increased their 1-RM strength. Their power did not improve though, indicating that again in less well-trained subjects, an interference effect may be present.
In concurrent training, the level of interference may depend on the training status of the athlete. More research is being done on concurrent training, but the data gained is dependent on the subjects involved. If untrained subjects are used, then maybe the conclusions are not relevant to experienced athletes. The interference effect may become relevant when you are trying to work at extremes of the energy system demands – ie pure speed and power, or aerobic capacity. For everything in between, concurrent training may be effective, especially for trained athletes. For beginners or novice athletes it may best to concentrate on one fitness aspect at a time, and if you are in a sport that places demands on all energy systems, training in 2-3 week blocks for each and rotating this throughout the season may be the best option.
30-minute sample workouts (based on twice-a-week training)
Remember to identify your main training goal for each week; and schedule the appropriate session first, when you are freshest. As you become fitter you can increase intensity rather than volume, as this is most likely to benefit you within a limited time. The advanced level workouts are very tough; you only need to include one of each type of session once each week, along with easier workouts and your team training.
- Warm up with 4 minutes jogging
- 30 seconds hard run, 15 seconds rest. Repeat 6 times, walking 1.5 minutes during recovery. Repeat routine 4 times
- Warm down – 3.5 minutes walking.
Strength (prioritising single-leg strength)
- Warm up, 30 body weight squats, 10 x single-leg body weight squats each leg.
- All following exercises now follow this protocol: 60% 1RM, 10 reps, 3 sets, 1 minute rest between sets:
- Bench press
- Single-leg squats
- Bent-over rows
- Abdominal crunches with medicine ball
- Back extensions with med ball.
- Warm up, row 500m at 50% maximum speed
- Row 18 minutes as far as you can
- Strength exercises, no rest move from one station to the next (will actually allow you 10 -20 seconds rest in reality):
- Bench Press 50% 1-RM 20 reps
- Pull ups – to failure
- Tuck jumps – 20
- Shoulder press 50% 1-RM 20 reps
- Bench hops – 20.
- Warm down – 3 minutes rowing at 50% maximum speed.
- Warm up 4 minutes bike ride to get heart rate to above 120bpm
- Maximal cycling effort for 20 seconds, 10 seconds recovery between – repeat for 8 sets
- 1min walk, 2mins jog, then maximal effort run for 20seconds, 10 seconds recovery – repeat for 8 sets
- 1min walk, row 2mins at 50% pace, then maximal effort for 20 seconds, 10 seconds recovery, – repeat for 8 sets
- Walk 3mins then as many burpees as possible in 20 seconds, 10 seconds recovery
- 3mins walk recovery to warm down.
Strength (prioritising maximal strength for whole body)
- All exercises: four sets of 5 reps at 85% 1-RM, 2mins rest between sets
- Military press
- Finish with hanging knee raises, 2 sets of 10.
- Dumbbell or weight disc pullovers
- Wood chops (hold weight by left foot and raise to above right shoulder, repeat on the other side, bend knees fully to lower the weight each time).
- Finish with Swiss ball rollouts, 2 sets of 20.
(to be performed against the clock or another athlete, maximal speed on the runs)
- Warm up with 3 minutes jogging.
- Run 800m, overhead squat 10 reps, bench press 30 reps
- Run 800m, 20 pull ups, 20 bench hops
- Run 800m, 10 deadlifts, 10 push press
- Run 800m, 10 dumbbell swings, 50 press-ups.
- Walk recovery.
James Marshall MSc, CSCS, ACSM/HFI, runs Excelsior, a sports training company
- Medicine and Science in Sports and Exercise 1996; 28(10):1327-30
- MSSE 1997; 29(3):390-5
- Journal of Sports Sciences 2005; 23(8):835-42
- MSSE 2005; 37(9):1601-7
- MSSE 2002; 34(11):1801-7
- Journal of Strength and Conditioning Research 2007; 21 (1):188-192
- JSCR 2007; 21 (1):23-28
- JSCR 2007; 21 (1):204-207
- MSSE 2006; 38/11:1965-1970
- MSSE 2006; 38/11:1950-1957
- British Journal of Sports Medicine 2005; 39(8):555-60
- International Journal of Sports Medicine, March 20 2007 (E-pub ahead of print)
- MSSE 2004; 36(12):2119-27
- European Journal of Applied Physiology 2003; 89(1):42-52
- JSCR 2001; 15(2):172-7