Wednesday, January 30, 2008

Interactions between training sessions – Part III: Interactions between swim-bike-run

In part II of this series, we saw how the time intervals between consecutive training sessions should be selected in order to respect the timings of adaptation to training for the different training methods used. Today I will talk a bit about how all this relates to the scheduling of swim, bike and run training sessions.

As an example of the timings that need to be respected in order to allow for adaptation to training, I quoted a table from Olbrecht (2000). As some readers surely noticed, those recovery times are very general and specific at the same time. General because they do not account for individual variability and specific because they apply to swimming training only. If the effect of individual variability is something easy to understand, it is worth noticing that in the context of swim training, training sessions almost always have the same length (volume), with different training methods being used inside the training session (intensity). That obviously simplifies modelling adaptation to training. For example, if we wanted to build a similar recovery chart for cycling training, where training sessions have varied length, we would need to either quantify training load (volume times intensity) or introduce some sort of temporal distintion.

So if for single-sport there are differences between recovery times, if we try to approach recovery timings in this way for triathlon training, the issue quickly becomes quite complex. As we saw before, fatigue is directly connected to recovery and adaptation to training. By modelling, even if qualitatively, fatigue and recovery, we gain insight on how the athlete is adapting to training. This is where the “art” in coaching comes into play. For the experienced coach, it is relatively easy to know what to schedule based on the information he has from the athlete and his experience in knowing the various responses to the various training methods. Most coaches, either consciously or unconsciously, model the fatigue levels of the athlete in order to prescribe training. Given the training load the coach feels is appropriate for the athlete, the training routine is set by asking the following question before scheduling the next training session: Will the athlete be able to complete and fulfill the goals of the next training session? Instead of setting in stone all the possible recovery times between all kinds of swim, bike and run workouts, a realistic accessment should be made as to the level of fatigue/recovery before each workout.

Intrinsic to this way of seeing daily training prescription, is the way we want to manipulate the athlete’s fatigue levels. Several approaches exist, most of them revolving around the concept of alternating “hard” days with “easy” days, that is to say, days where fatigue level is high with days where fatigue level is low. However, I find that the easiest model to implement is one of fairly constant fatigue levels. This will bring fairly constant recovery timings and hence very predictable responses to training, i.e. adaptations. It is obvious that one possible way of obtaining fairly constant fatigue levels, which will in turn produce predictable responses to training, is to apply fairly constant training loads. However, when scheduling triathlon training, the concept of equivalent training load between swim, bike and run is one difficult to estimate. Again that is where experience in triathlon training prescription is important for the design of the best training schedule.

During this short series, I broadly definined an approach to training prescription based on modelling the level of fatigue as a way to model recovery and adaptation to training. When talking about training, most discussions are centered around what training load should be applied to the athlete, and very seldom the characteristics of the response of the athlete to the load is mentioned. It’s as if the way the athlete handles the training sessions is not important. Modelling the athlete’s fatigue when prescribing training, even if in a qualitative way, puts the athlete back into the equation and allows us to design more effective training plans that cater to the athlete’s individual response to training.

Wednesday, January 16, 2008

Interactions between training sessions – Part II: Timing of adaptations

In the first instalment of this series, I talked a bit about the importance of modeling the response to training load, fatigue and recovery, to the correct prescription of training. Today I will talk a bit about the temporal evolution of fatigue/recovery, which will influence adaptation to training.

After each training session, fatigue sets in and performance is diminuished. The recovery process also starts as performance will slowly increase towards a higher level. The recovery phase allows for several biological adaptations to occur:

- normalization of the cell environment.
- recovery of neuromuscular stimulation processes
- concentration and activity of enzymes and hormones will be restored
- energy sources are replenished

As these processes evolve, adaptation to the stimulus (training session) is marked by an increase of performance. This is usually called the principle of super-compensation.

As fatigue is directly related to performance, and performance related to adaptation to training, then one way of monitoring adaptation would be to measure performance. However, measuring performance has its own impact on the training process. Therefore, a non-intrusive way of monitoring adaptation to training is the qualitative monitoring of an athlete’s level of fatigue.

In order for adaptation to training to occur, some requiments need to be met:
- A healthy body: Inflammation, infection, mental stress, etc strongly reduce the possibility for adaptation.
- Adequate training load: This is the most crucial aspect of successful training.
- Enough recovery: rest or regenerative workouts will make up most of an athlete’s time.

The timing for adaptation is the deciding factor when planning training on the short-term (1-7 days). For a healthy athlete, this timing depends on several factors:

- the type and duration of the workout
- the conditioning level of the athlete
- the recovery level of the athlete

If an athlete has a high conditioning level and/or is well rested, time for adaptation will be shorter. On the other hand, mental stress or lack of rest will slow down the process necessary to achieve super-compensation. The differences in timing for adaptation are due to various biological regeneration processes that take place during the recovery phase. The replenishment of creatine phosphate will take only a few seconds to a couple of minutes to return to normal levels, but the glycogen-reloading process in the muscle may last 24 hours; in some cases, it may last even longer. The production of new enzymes (proteins) may also take hours, sometimes even days, to complete (Olbrecht 2000).

According to Olbrecht (2000), the time for different types of training to reach the maximal supercompensation are:

- Extensive Endurance: 8 to 12 hours.
- Intensive Endurance: 24 to 30 hours.
- Sprints/Short sets: 30 to 40 hours.
- Extensive Anaerobic Training: 36 to 48 hours.
- Extensive Strength Training: 40 to 60 hours.
- Intensive Anaerobic Training: 36 to 48 hours.
- Intensive/Strength Training/Competition: 48-72 hours.

When designing a training plan, the time intervals between consecutive training sessions should be selected in order to respect the timings of adaptation to training for the different training methods used. Working out these timings is possibly the most difficult part of planning and it is the "art" part of coaching.

In the last part of this series, I will talk a bit about interactions between swim, bike and run training sessions.

Olbrecht, J., (2000), The Science of Winning – Planning, Periodizing and Optimizing Swim Training.

Wednesday, January 9, 2008

Interactions between training sessions – Part I: Load, Fatigue and Adaptation

A fundamental problem in training planning is the way you sequence the various training sessions inside one micro-cycle. Even though this problem is present for any sport, when it comes to triathlon training it assumes a particularly important role. Due to the different characteristics and muscle groups involved in swim-bike-run, it is often hard to see how the interactions between training sessions effect training adaptations.

The training process can be loosely modeled as a series of sequenced processes composed of:

Training Load (session) -> Fatigue -> Adaptation(recovery) -> Performance

Obviously the training load imposed is a central aspect of training planning. However, fatigue plays an important role in the whole training process. In this context, fatigue can be defined as a natural response to a training load characterized by a lessened capacity for work. The evaluation and monitoring of the level of fatigue of an athlete, either quantitatively or qualitatively, a priori or a posteriori, is the most accurate way of checking the level of an athlete’s adaptation to training. Fatigue has several characteristics, but when it comes to planning training, we are mostly interested in fatigue as a function of time.

It is intuitive to everyone that different training sessions cause different levels of fatigue and that, more important, have different time-frames to recover from and to adapt to. Sessions with a higher training load take more time to recover from than sessions with a lower training load. When designing a micro-cycle routine, the temporal characteristics of the fatigue caused by a specific session need to be taken into account. On top of that, the interactions between the several Load -> Fatigue -> Adaptation processes need to be estimated in order to access the fatigue status at a given time. This fatigue status is extremely important because it determines the maximum load an athlete can perform at a given time.

Like I mentioned above, evaluating and monitoring fatigue can be done both quantitatively or qualitatively. For years and years, coaches have been predicting, evaluating and monitoring athlete’s fatigue levels in a qualitative way, in order to prescribe training. And rightfully so, since only through monitoring fatigue we can evaluate adaptation to training. Many coaches and athletes see training as a mere accumulation of fatigue, expecting that rest periods (days, weeks and even months) will be enough to recover from fatigue and allows for adaptations to training to happen. This way of thinking fails to realize that recovery occurs at all times that stress is not applied, and that adaptation to stress occurs at all times, even while stress is applied. Correctly modeling fatigue, even if in a qualitative way, is paramount for a correct prescription of training.

In the next part of this series, I will talk a bit about how the level of fatigue is connected to the level of recovery, the timings of fatigue/recovery and how all that that determines micro-cycle planning.

Tuesday, January 1, 2008

Some thoughts about improving running technique with the help of the KISS method

Note: I wrote this in 2005. Reading it now, there are certainly some things that I don't agree with, but as a whole, it reflects my thoughts about running technique. The "book readers" among you will recognize some passages of a well-known running book.

The school of thought that argues that one's so-called natural style is not only best but unchangeable represents a defeatist attitude. It ignores the reality that the nervous system has great adaptive capabilities to incorporate subtle changes in data input that create an improved movement pattern. In so many sports-golf, tennis, swimming, gymnastics, and more-the guidance of coaches expert in designing corrective exercises and instructional commands can bring observable changes in style that contribute to improved performance. The same can occur in running.
With each running stride, the muscles of the landing leg store impact energy as they contract eccentrically to absorb the shock of landing. Most of the stored energy is then used during the concentric muscle contraction that propels the body forward during the next stride; that is, we use the impetus of landing to assist the muscular effort of takeoff.
Indeed, there is growing evidence to suggest that the elastic recoil provided by the tendons contributes a significant proportion (about 30%) of the energy for propulsion, at least when running on flat terrain. It is possible that the muscles of the more economical runners have a greater ability either to store or to utilize this form of impact energy.
A popular idea, implicit in the description of how muscles work is that it is the shortening of contracting muscles that propels the body forward when we run. But running is really a series of bounces in which muscles, tendons, and ligaments alternately store and release the energy absorbed as the feet hit the ground. Indeed, it is similar to the action of a pogo stick or a bouncing ball. The realization that the legs alternately store and release elastic energy during running, that this elasticity probably contributes to running ability and possibly also explains some forms of exercise exhaustion.
The most current biomechanical model of leg action during running is that all the elastic elements in the lower leg muscles act as a single linear spring. The stiffness of that spring can be varied, however, particularly in response to the softness of the surface over which the athlete runs. This is important because the stiffness of the spring determines how the body reacts with the ground during the contact phase of the running cycle.

I believe that good running technique is based on the following three aspects:
- Stride frequency – Keeping it above 88 cycles/minute
- Stance time/Support time – Keeping it as short as possible
- Point of impact – Keeping it below the center of gravity

Associated with these three aspects, which can be called primary, are secondary aspects that basically relate to balance issues:

- Upper body balance
- Head position
- Correct tracking of the lower limbs

Primary aspects

Stride frequency

Daniels is the author that emphasises stride frequency more. Upon studying the stride frequencies of runners in the 1984 Olympics, he found that elite runners from distances from 400m to the 10000m use stride frequencies above 90 cycles a minute.
Most average to good runners, even those with evident technical deficiencies, employ a stride frequency above 90. This variable is also a good way to find runners with a poor technique, so it is always a good point to start when working with new runners.
The stiffness of the leg spring is independent of running speed but alters with changes in stride frequency. Thus, at the same running speed, the leg spring becomes stiffer the higher the stride frequency (and the shorter the stride length). The stiffer the spring, the less energy that will be absorbed. These findings suggest that the naturally chosen stride frequency when running at the same speed by different runners (of similar mass), must reflect individual differences in the elasticity of their legs.

Support time

About this technical aspect, I’m always reminded of a quote from Chariots of Fire. When working on the track with the athlete, the coach says “Run like you’re running on a hot plate”. When trying to minimize the support time, that is the exact feel that we want to achieve.

Point of impact

Having the point of impact on the ground as below was possible to the center of gravity (CG) of the body is very simple biomechanics. The further forward the point of impact is from the body’s CG, the longer the “braking” phase of the stride, since forward aceleration can only occur after the support point passes the vertical of the CG.

Secondary aspects

Upper body balance

The shoulders and upper arms are also important in running. Though they primarily provide balance at relatively slow speeds, they increase in importance in assisting the leg muscles as running velocity increases and as a runner climbs hills. Adequate arm and shoulder interaction reduces the need for counterrotation of the trunk musculature, which is more energy wasteful. Efficient running style suggests that the arms swing fairly loosely and be held quite naturally. Neither should the shoulders be hunched or pulled back, nor the chest thrust out in front. Unnecessarily tensed muscles suggest a needless waste of energy. The shoulders should be carried above the hips.
Arm action varies with running velocity; it is much more vigorous at faster than at slower velocities. Elbows kept close in toward the body minimize the tendency for the hands and lower arms to cross the midline of the chest. Hands and arms normally should only approach the midline. At a wide range of running velocities the elbow joint is flexed at about 90° and remains that way through the range of arm swing. However, at very fast racing velocities this elbow flexion angle unlocks and varies on either side of 90° to provide more fluidity. Arm swing and leg action are inextricably interwoven. If arm swing tends to be erratic, it detracts from optimal style and is energy costly. The hands should be kept loose and relaxed at all times.

Head position

The head should be poised well above the shoulders. It is a very heavy piece of anatomy, and if it is not positioned properly, it can cause either of two problems, both bad. If it is too far backward, it places an unnecessary strain on the neck muscles. If it is too far forward, it can restrict the airways and make breathing difficult.

Correct tracking of the lower limbs

This aspect is best exemplified by watching sprinters running. Every movement they make is towards the direction of motion, especially the lower limbs. For a correct tracking of the limbs, a correct activation of the hip flexors is very important.

Up-and-Down Movement
There is evidence to suggest that uneconomical runners expend more energy bobbing up and down when they run than do more economical runners, who tend to glide over the ground with very little vertical oscillation. Clayton has described how he thinks he became an economical runner:
“When I started training for marathon distances, my style changed naturally. Running 20 miles a day cut down on my stride length. It also eliminated the tendency to lift my knees. Gradually, my power stride evolved into one of economy. Despite the energy-draining action of my upper body, I developed a very natural leg action I call "The Clayton Shuffle. " Through miles and miles of training, I honed my leg action to such a degree that I barely lifted my leg off the ground. "The Clayton Shuffle" is probably the best thing that ever happened to my running. It was economical and easy on my body.”