I received an email with some great examples of the value of rest and questions about the influence of conditioning…

Question: “Hi Coach Back… I had great success with your original program and I had a couple questions. 9 years ago I discovered the overshoot phenomenon on accident. In high school weight training we did cross fit almost 5 times per week. it was a lot of strength work and conditioning. I got fairly strong (I BS 300# weighing 170#). Immediately after that semester of crossfit rugby season started, so it was more conditioning and I kept weight training during the week, ( me and my friends were gym junkies). I was somewhat fast but nothing crazy. Two months into the season I had a nasty high ankle sprain that kept me out for over a month. I didn’t do anything for two weeks and lightly did the stair master for a few weeks. Six weeks after the injury I was warming up in the ball court to test how high I could jump and I could hang on the rim from a stand still. Before all I could do was grab the rim from a running start, and from then on during games I blew by everybody for the rest of the season. That was my experience and it was awesome. When I did your original jump science program I was also getting conditioning work in by playing basketball a few times a week along with your strength and explosive training. After just ten days rest I saw a huge jump in speed and vertical. The second time I did your program I strictly followed it but without the added basketball so no conditioning work. I got stronger than I was before and my vert increased during the program but during the rest times my vert stayed the same. My question to you is if you had had experience with a little conditioning along with your explosive and strength training to add more slow twitch fibers during the training but in the end experience a higher overshoot then with just plyos and strength training alone? Sorry for the long email but I found it pretty interesting, my training partner also experienced the exact same results.”

Answer: “I definitely think there is validity to the trend you’ve noticed. But let’s talk about the mechanism behind it. Some things to consider…

First, let’s be clear that an overshoot in performance is not the same thing as the overshoot phenomenon in FT fibers, although that certainly plays a role. Obviously there are factors besides muscle fiber typing that influence performance and contribute to fatigue / overshoot. I think the overshoot phenomenon definitely occurred when you had the 6 weeks off from your ankle injury. When you had the 10 days rest, your muscle fibers probably did begin to shift back in a fast direction, but I doubt that was enough time for overshoot to occur. The overshoot in performance was probably mostly due to nervous system recovery in that case.

Conditioning on top of a power development program would increase the shift in a slow direction by muscle fibers. Since the conditioning in this case is still an explosive sport, it is possible that it contributed to a bigger fiber overshoot. But definitely I would say that it increased the stress on the nervous system and contributed to a greater adaptation there. I suspect that is the bigger factor.

We also need to consider the value of training volume. I’ve posted on this before (Beware of the Explosion Principle). The volume of playing basketball is great for structural strength. Maintaining structural strength is one of the challenges of rest or easy training periods. Rest is great for the nervous system, but it can lead to your muscles and tendons wasting away. With volume in your training you build up that structural strength, which allows you to rest more without losing it really fast.

Altogether, I think playing a multi-directional sport is a great stimulus to have in training. The value comes from the benefit of training volume, the increased stress and hopefully subsequent adaptation by the nervous system, and possibly a larger overshoot in fiber twitch speed during a recovery period.”