Ed McNeely – Peak Centre for Human Performance

Interval training is a popular form of training amongst many athletes. While most rowers will use intervals at some point in the year few really understand the purpose of intervals or how get the most from this valuable training method.

 Physiology of Interval Training

Interval training involves alternating periods of high intensity work with periods of lower intensity work, usually, but not always above and below anaerobic threshold. By alternating periods of higher intensity work with lower intensity work several things are accomplished:

The amount of high intensity work is maximized. If you were to try to hold an intensity above anaerobic threshold for as long as possible you would fatigue in just over 20 minutes. If you were to do 6 x 5 minute work intervals with a rest period in between you would have done 30 minutes of work above threshold. Since the volume of work above threshold was higher it should give you a greater training effect. The same holds true for VO₂ max and anaerobic intervals.

During the work period of the interval you will be producing lactate and other metabolic by probducts, which your body will have to deal with during the rest period. Active slow twitch muscle fibers are capable of using lactic acid as an energy source. Repeatedly exposing your body to moderate levels of lactate and then allowing it to recover gradually trains your body to become more efficient at lactate removal as your body develops the enzymes necessary to convert lactate back to glycogen or glucose. This will translate into lower lactate and faster times during a race since you will be able to deal with the lactate as it is produced. Of course this training effect will only happen if you have done adequate base training.

The aerobic capacity of fast twitch fibers is improved with interval training. The more often a fiber is activated the greater it’s oxidative capacity. Interval training is the only ways to activate the fast twitch fibers frequently enough to improve their aerobic capacity, making them behave more like slow twitch fibers.

 Designing an Interval Training Program

Interval training is high intensity and needs to be planned very carefully in order to avoid overtraining. The most important component of an interval program is the base work that is done prior to starting intervals. The initial 6-8 weeks of your training should be devoted almost exclusively to low intensity long duration training, 60 minutes or more per session. This will prime the slow twitch fibers and improve their fitness, so that they can accept the lactate that will be produced when intervals are started, allowing you to make effective use of interval training.

The Work Period

The duration of the work period will vary depending on the intensity of the interval. A work load just above anaerobic threshold will need long intervals, 5-10 minutes, while higher intensity anaerobic intervals can be as short as five seconds. Consistency is the most important factor in interval training. The power output or split time should be the same for each work piece of an interval session. In other words if you are doing 5 minutes at 200 watts  on the first interval all other intervals should be done at the same pace. This ensures that you are maintaining the appropriate intensity and recruiting the same muscle fibers in each interval, improving the training effect. It does very little for you to do an interval session where the first interval is 18 km/hr the next is 16 km/hr the next 15 km/hr etc. Be sure to choose an interval duration and split time that allows you to be consistent throughout the workout.

Choosing paces for the work intervals requires a little up front work on your part. You need to have an idea of your splits for both anaerobic threshold and VO₂ max.

The Rest Period

The rest period is as important as the work period. The purpose of the rest period is to allow time to remove the lactate created during the work interval, and allow the anaerobic alactic energy system to replenish itself. During aerobic intervals, intervals longer than two minutes, the rest period is active, meaning you continue to row but at a lower intensity. The duration of the rest period will depend on the duration and intensity of the work period. Aerobic intervals will vary for a 1:1 to a 1:4 work rest ratio. Anaerobic intervals were covered last year in another article. When choosing the duration of your rest period, follow these simple guidelines: 1). The longer the work the shorter the rest

Longer intervals are normally done at lower intensity, requiring a shorter rest period. A five minute interval just above anaerobic threshold will produce moderate levels of lactate requiring less time to recover so a 1:1 or 1:1.5 work to rest ratio can be used. A higher intensity two minute interval will produce more lactate and therefore require a longer recovery. 2). Adjust the duration of the rest period so that you can maintain a consistent split during the work period. It may happen that you decide to do 5 minutes of work followed by 5 minutes of rest, repeated 5 times. Half way through the workout you notice that you can’t hold the same work split. Finish the training session, coming as close as possible to the desired splits. For the next session increase the duration of the rest period by 50%. If you still cannot hold the desired splits for all the work periods drop the splits for the rest period by about 10% for the next workout.

Table 1: Work and Rest Period for Various Interval Intensities

Most athletes will use some combination of all four types of intervals in their training program. For those doing short races, less than 30 minutes the VO₂ max and anaerobic sprints should make up the bulk of your interval training, while those doing only longer races will focus their interval training on anaerobic threshold intervals.

While interval training is a great way to improve speed, it is easy to overdo it and do yourself more harm than good so take it easy when starting by doing only one session per week and increasing by one session per week every two weeks until your are doing at most three sessions per week.

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PEAK Centre staff have the highest certifications available in Canada for Sport Science. With their combined experience and education, PEAK Centre is at the forefront of practical Sport Science application.

Ed McNeely – Peak Centre for Human Performance

VO₂ max is one of the most commonly measured physiological variables. Endurance athletes spend countless hours discussing, comparing and worrying about their VO₂ max scores. Runners are always quoting VO2 max scores for one top athlete or another. Is all the attention that this physiological variable gets really worth all the effort?

VO₂ max is the maximum amount of oxygen that your body can take in and use. It is a function of both the body’s ability to deliver oxygen via the heart, lung and blood and the body’s ability to use oxygen in the working muscles and other tissues.  While there are some exceptions, Elite runners typically have VO2 max scores in the 70-75 ml/kg/min range, similar to that seen in well trained amateur runners and some very fit age group runners. Your ability to have a high VO2 max is very dependent on your genetics. While other training variables like strength can improve by 100% or more VO2 max changes are limited to about 20% once you reach full physical maturity.

In aerobic sports oxygen consumption is tightly tied to energy expenditure and generally producing more energy means more power and work. The relationship between power and oxygen consumption is not perfect; efficiency or economy play an important role in determining how strong the relationship is in each person.

Running Economy, the ratio of power output to power input, is a key determinant of running performance.  A higher efficiency allows a runner to work at lower percentages of the VO₂ max to accomplish the same or more work as a less efficient runner. In fact, a high economy rating can make up for lower VO₂ max scores. Some measures of East African runners have found world class running performances, running 1500m in 3:35 or better, despite VO2 max values of only 63 ml/kg/min. This is roughly the same VO2 max score as a good age group runner and about 20% lower than would be expected for a runner with this type of performance.

Improving economy can have a significant impact on your running performance. There are several ways to improve running economy:

1. Focus on technique – running stride and technique are key to running economy. Get a coach who will work on improving your running mechanics and who can do a proper gait analysis.
2. Strength training – strength and power training have been shown to increase running economy by as much as 7%
3. Altitude training – altitude training or intermittent hypoxic training, as outlined in a previous post, improves oxygen use in the body allowing more energy to be produced by the aerobic energy systems, which are more efficient.

Running economy is an area where many recreationally competitive runners can make a lot of progress when they think they have plateaued. Get your economy assessed and find out if it is limiting your performance and build a plan that will help make you the most efficient runner possible.

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PEAK Centre staff have the highest certifications available in Canada for Sport Science. With their combined experience and education, PEAK Centre is at the forefront of practical Sport Science application.

By Ed McNeely – Peak Centre for Human Performance

Training without monitoring your progress is like driving with your eyes closed, you will get somewhere but you can’t be sure where or what shape you’ll be in when you arrive. Through daily monitoring you will be able to make the fine adjustments to your program that allow you to continue to progress and recover at the fastest rate possible.

Although many people dislike math or the thought of math, numbers are your friends when it comes to developing rowing fitness. Recording time, rate, speed, bodyweight, and heart rate provides a basis for measuring and monitoring training sessions and the program as a whole. The numbers are not the whole story, they will tell you what is happening in a training session but don’t help explain why, you need to combine training data with recovery data that measures sleep, soreness and other physiological parameters that will show whether you are heading towards an overtraining state or not.

Over the years many physiological tests have been developed to try and measure recovery and guide training programs. Blood urea, creatine kinase, hormone levels and ratios, and blood amino acid profiles are just some of the tests that have been used. If you are an elite professional making millions of dollars per year and have access to top medical and physiology labs and consultants these tests are probably worth using. For everyone else there is a much simpler way that has been shown to be as effective as all the expensive blood work; the recovery questionnaire.

The Recovery Questionnaire

The recovery questionnaire is filled out every day of the week whether there is a workout scheduled or not, you want to be able to measure the effect of a day off as well as a training day. A 2-3 week baseline should be established in the off-season when you are doing little or no training. The baseline is used to measure how far from a fully recovered state you are moving as a result of training and will be referred back to every week so keep the baseline numbers handy.

Each of the items in table 1 are rated on a scale of 1-10, using half points as well as whole numbers. Low numbers are better ratings for example a rating of 1 on quality of sleep means you had a great nights sleep, a 10 might mean you were up most of the night. The ratings are based on how you fell when you first wake up and get out of bed in the morning. Be honest with yourself, as you will use this information to adjust your program. Body weight should be measured after voiding and before breakfast so that conditions for the weigh in are standardized. Morning heart rate is measured as soon as you wake up. Keep a watch by your bedside and take a 30 second heart rate count and multiply it by two to get the number of beats per minute.

Table 1. Recovery Questionnaire

Using the Data to Adjust The Program

All data is compared back to the baseline established in the off-season. No single variable can assess recovery; the power of the questionnaire comes from the use of multiple variables simultaneously. If you see an increase of two points on the unshaded variables, compared to the baseline, on three or more variables two days in a row you need to take a day off or cut both the volume and intensity of the day’s training in half. If the week average of three of the unshaded items increases by three or more points you need to schedule a recovery week, even if one is not planned in the program.

Morning heart rate and body weight are not included in the daily and weekly analysis because changes in these items are much more gradual than the other factors that are being monitored. Increases in morning heart rate of more than 10 beats per minute for a week or more should be looked at closely, if it is occurring without changes in any of the other variables it may signal a loss of aerobic fitness which may or may not affect your performance depending on the endurance demands of your sport. If the weekly average is increasing and morning heart rate is high you need to consider planning a recovery week.

Unintentional decreases in bodyweight are one of the early signs of overtraining. Body weight can fluctuate daily because of hydration levels and what you ate and drank the previous day. Very large athletes can see their weight change by several pounds from day to day; because of this it is better to use weekly percent changes in body weight to assess your long-term weight profile. If you see a weekly-unintended weight loss of more than two percent something needs to be adjusted in training or diet. First increase fluid intake to see if you are dehydrated because of the week’s training schedule and insufficient fluid intake. If the weekly average of other variables is increasing and bodyweight is decreasing there is a good chance that you are beginning to overtrain and need to schedule a recovery week.

Regular monitoring of recovery will help you adjust your training program and give you an idea of the effect that various workouts have on your body. Combining recovery measures with the information on boat speed, perceived intensity of a workout and work time will allow you to dial in your training program and ensure the fastest rate of progress.

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PEAK Centre staff have the highest certifications available in Canada for Sport Science. With their combined experience and education, PEAK Centre is at the forefront of practical Sport Science application.