Sunday, 26 April 2015

The "Overshoot Phenomenon" (Part 3)

We have now observed the "overshoot phenomenon" occur in two separate studies Andersen et al. (2000 & 2005). However, these were both seen in sedentary subjects where long periods of detraining are not going to affect performance as it would in professional athletes. One study has looked at the "overshoot phenomenon" in a professional team sport setting but rather than observing changes in muscle fibre type, performance based variables were implemented (de Lacey et al. 2014).

So what were the characteristics of the subjects?

Seven professional rugby league players from a National Rugby League Club, including 2 international players (age: 24 ± 3.6; height: 183.0 ± 6.1cm; weight: 99.0 ± 12.2kg).

What was done leading into the tapering period?

Four months of preseason training consisting of resistance (weight) training was performed 3-4 times a week averaging approx 60mins a session. Field sessions (fitness and skill sessions) were performed 3-4 times a week averaging approx 60mins a session. 

What is a taper and when and how was the taper structured?

A taper is a reduction in training load over a period of time with the aim to reduce stress on the body and mind of daily training and optimise sport performance. Reducing the training load can be done by manipulating training intensity, volume, duration, frequency and mode. 

In this study by de Lacey et al. 2014, a step taper was implemented 21 days out from the start of the first round of the NRL season. A step taper is where training load is suddenly reduced rather than gradually. In this instance, the reduction of training load was manipulated by the reduction in training volume while intensity (how heavy you lift) remained high. 

During the taper, the subjects performed only 1 resistance training session each week while field sessions remained the same.

What was measured and how?

To keep this simple and least sciencey as possible, I will make this brief. 10 concentric only squat jumps were performed by each athlete using ascending loads, with 2 jumps being performed at each load (0, 25, 50, 75 & 100% body mass). Jump height was measured with a linear position transducer and using some additional leg measurements, a force/velocity profile was constructed for each subject. This was done both pre and post taper.

Before we go into the results, here are some definitions of variables that were used to make this easier to understand.

F0 - theoretical maximum force (i.e. the amount of force that the subject can produce and zero velocity)

V0 - theoretical maximum velocity (i.e. the velocity the subject can produce at zero load)

Pmax - maximal power (i.e. the product of F0 and V0)

Sfv - the slope of the force/velocity profile. This is determined by F0 and V0.

NOTE: I will explain the importance of the force/velocity profile in another post as it will make this already long post even longer.

What happened from pre to post taper?

Pre Taper
Post Taper
F0 (N/kg)
54.93 ± 25.71
64.74 ± 16.87
0.45 (0.05;0.85)
V0 (m/s)
2.71 ± 0.63
2.86 ± 0.58
0.24 (-0.44;0.91)
Pmax (W/kg)
34.87 ± 10.97
44.71 ± 6.72
0.85 (0.46;1.24)
-22.39 ± 14.09
-24.09 ± 9.69
0.23 (-0.26;0.72)
Jump 25% (cm)
39.59 ± 8.52
47.74 ± 4.65
0.90 (0.20;1.60)
Jump 50% (cm)
31.66 ± 8.49
42.09 ± 4.63
1.04 (0.65;1.42)
Jump 75% (cm)
25.41 ± 9.13
36.39 ± 6.49
0.94 (0.58;1.30)
Jump 100% (cm)
21.20 ± 9.51
30.30 ± 5.08
0.83 (0.38;1.28)
Unclear, *Likely positive, **Very Likely positive, ***Most Likely positive, F0= theoretical maximum force, V0=theoretical maximum velocity

Table 1. Results from pre and post taper

From the table above, we can see a likely small increase in F0 while improvements in V0 and Sfv were unclear. Pmax and the four performance variables however showed likely to most likely moderate increases from pre to post taper.

Did an "overshoot" occur?

While muscle biopsy's were not taken in the present study, we can assume an "overshoot" did not occur as velocity capabilities changes were unclear as well as changes in Sfv. As explained in part 1, Type IIX muscle fibres have the fastest contraction time of all the muscle fibre types so more Type IIX muscle fibres would mean a greater V0 which did not occur. Also, Sfv became slightly more negative indicating the slope of the force/velocity profile moving towards force capabilities rather than velocity.

So what does this all mean and what can we do with this information?

In a short roundabout way, this data suggests that a 21 day taper is long enough to illicit a positive change in maximal power AND performance. These positive changes seem to be influenced by the increase in force capabilities rather than velocity which goes against the study by Andersen et al. (2005) explained in previous parts. One of the potential reasons for this was the taper length as the present study tapered for 21 days while Andersen et al. (2005) detrained for 3 months. For a professional athlete, this would never be possible. Therefore, a short step taper implemented in this fashion leading into a season could be used to "peak" athletes for their first competition game.

There are many things we still don't know when it comes to tapering, force/velocity profiling and "overshoot." E.g. how long do these changes last? Do these changes affect any other areas of performance i.e speed? What is the optimal taper length to illicit the greatest positive changes? Can we do this during the season to peak for playoffs? Hopefully these questions can be answered in future research.

I know detail was brief but this was going to be far too long if I added all the details. I will write a separate post with more details about force/velocity profiling and why it is such an important part of a strength and conditioning program.