Interval Training – What Ratio Is Best?

In previous blogs, we have explored how a personal trainer can utilise interval training to motivate clients and progress their fitness, as well as the fat-burning zone – a marvel or myth? In this week’s blog, we examine interval training ratios.

WHAT IS INTERVAL TRAINING?

Interval training is used in personal training and gym programs to enhance results for individuals, ranging from regular gymgoers to those participating in high-level sports and athletics.

It involves a period of work followed by an active or passive rest period.

High-Intensity Interval Training (HIIT) is currently very popular. It has remained in the top three of the Worldwide Survey of Fitness Trends released by the American College of Sports Medicine (ACSM) since its first appearance on the list in 2014 (see our blog on the Results of the 2017 Worldwide Survey of Fitness Trends).

TARGETING THE THREE PRIMARY ENERGY SYSTEMS

You can use interval training to target all three primary energy systems: the creatine phosphate system, the aerobic system, and the lactic acid system.

AEROBIC RATIO

Ratio: the aerobic ratio is: 1:1 to 1:0.5. This is to suggest you would start at the highest ratio (1:1) and over time progress on to the harder ratio (1:0.5)

This equates to four minutes of work followed by four minutes of rest, repeated the desired number of times. Alternatively, you could alternate between 4 minutes of work and 2 minutes of rest, performing the desired number of repetitions.

Minimum work duration: To ensure that the energy system used is aerobic and not lactic acid, the minimum work duration should be two minutes.

Maximum work duration: depends on the individual’s goals. If they are training for a marathon, they might conduct 1- or 2-mile intervals. These could be four-minute miles to 15-minute miles, depending on their ability and fitness levels. For recreational use, a two-minute interval would be more appropriate.

LACTIC ACID RATIO

Ratio: the lactic acid ratio is: 1:4, 1:3 or 1:2. It is recommended you start on the highest ratio (1:4) and progress down the ratios as your lactic acid tolerance and lactic acid removal pathways improve.

This equates to: one minute of work followed by a four-minute rest, or 30 seconds of work followed by a 90-second rest, or 30 seconds of work followed by a 60-second rest. Each protocol would be repeated for the desired number of reps.

Minimum work duration: 15 seconds, to promote the use of the lactic acid system rather than the ATP/CP system (creatine phosphate).

Maximum work duration: This will vary depending on fitness level and lactic acid tolerance. For example, a highly trained athlete will be able to maintain a higher output for a more extended period, resulting in higher lactic acid levels. Generally, you won’t be able to maintain a high (lactic acid generating) output for longer than 2–3 minutes.

Please note that recent research suggests shorter or inverse ratios, such as 2:1 (20 seconds on followed by 10 seconds of rest), also known as Tabata training, have been shown to bring excellent benefits. Research conducted by Dr. Tabata showed that individuals who performed 20 seconds of maximal effort followed by 10 seconds of passive recovery, repeated 8 times, had greater anaerobic fitness, greater aerobic fitness, a lower body fat percentage, and an increase in muscle mass when compared to individuals who exercised at 70% for 60 minutes.

Creatine phosphate (ATP/CP) ratios

Ratio: 1:6 or higher, up to 1:50 (or higher)

This equates to: 10 seconds of work followed by 60 seconds of rest, or even five seconds of work followed by 250 seconds (4 minutes 10 seconds) of recovery.

Minimum and maximum work duration: This will depend on the type of explosive fitness required by each individual. For example, Usain Bolt needs a large ratio to ensure that every time he trains, he is working as fast as possible with minimal fatigue. An average gym-goer might find satisfaction in using a rower for 10 seconds, then taking a 60-second break to enhance their energy system.

It is worth noting that regardless of the type of interval training used, the result will always lead to an improvement in cardiovascular fitness. A 2001 study titled “Energy System Contribution During 200- to 1500-M Running in Highly Trained Athletes” by MR Spencer and PB Gastin demonstrated the following aerobic energy contributions during various running events:

• 29% for 200m
• 43% for 400m
• 66% for 800m
• 84% for 1500m

The results revealed that the aerobic energy system played a more significant role during high-intensity activities than previously believed.

CONCLUSION

An overarching benefit of interval training lies in its ability to utilise and overload most energy systems. This process promotes a potent stimulus for the development of clients’ aerobic, lactic acid and ATP/CP energy systems. As always, the key is specificity to a client’s level of fitness, goals, and other factors, as well as how you will promote overload to ensure progression.