Joel Smith is the founder of Just Fly Sports (www.just-fly-sports.com), an excellent training site all about jumping high and running fast. He is currently the head Strength and Conditioning coach, assistant Track & Field coach, and adjunct professor of Sports Science at Wilmington College, Ohio, USA.
Joel sent me some questions for an article on his web site, here is what I wrote:
Joel Smith (JS) – What are your thoughts on box height in depth jumping?
Simon Hunt (SH) – The point of jumping off a box is to add the force of the body falling to preload the muscles so they can contract more powerfully when you rebound off the floor. This requires a quick contact time of under 0.25 sec to utilise the energy stored in the ligaments and tendons in the rebound jump. A longer contact time results in this energy being lost. A good jump is a refection of the power output of a athlete. High jump = high power output. Power is a function of force and time. The relationship between the amount of force and how fast an athlete is dealing with it is crucial in coaching good technique and training. Most studies show that jumping off a box height of over 60 cm does not increase power output. This is because the force the athlete is dealing with is to large for them to rebound off the floor under 0.25 sec, and the resulting jump is no higher than a static jump. The same effect can be observed by increasing the passive weight of the athlete with a weighted vest. Effectively there comes a point where the athlete is not performing a rebound jump but is just jumping off a box landing and then jumping again, as two separate movements. The best indicator that the box is too high and the power output is being reduced is a reduction in the height of the rebound jump. So just follow the simple rule that you must be jumping high to be training your jumping. Low jump training does not work and I don´t like it. So fundamentally the box is there to help you jump higher, not lower which is what happened to most people jumping off a over 60 cm box.
Sets & reps: 200 reps per session (250 max) 2 sessions per week MAX. Most studies show that 3 times a week is detrimental to jumping, this is true in my own experience as well.
Do not start plyometric training until you can skip rope consistently for 5 mins (Approx 150 – 160 light contacts per min = 750 – 800)
JS – What are your thoughts on the practice of single leg depth jumps or single leg hurdle hops?
SH – This is a difficult exercise to get right. Basically you must be technically perfect. Considering the forces that I have described above involved in two legged depth rebound jumping, removing a leg from the equation will lead to a doubling of the force. So to keep the contact time below 0.25 sec you must halve the height of the boxes, and I would halve the number of contacts to begin with as well. The training forces on the body are high doing this which means the performance pay off must be well worth it. I´m not sure it is as you can have the same effect with easier exercises. There is no need to complicate things or add unnecessary risks in my opinion. I personally started single leg hurdle hops when I was recovering from a torn Achilles, using my good leg. This was mainly because it made me mad to watch my training partner Luke Crawley jumping while I could not, so I bet him I can do it off one leg. I like to use single leg contacts in continuous box jumping with a single foot on the box and two feet on the floor. Small technical hopping over very low hurdles is best to start with. If the upper body begins to learn in ANY direction (usually forward first) during the hop then reduce the hurdle height. Above all keep this exercise for training technique.
JS – What are your thoughts on the use of maximal strength training (over 90% 1rm) in track and field athletes?
SH – Brilliant! But only in weight lifting exercises NOT powerlifting. By this I mean clean,
snatch and squat. Not deadlift. I use 90% in the competition phase of training that last for 6 weeks. 3 sets of 3 reps each at 90 – 95% max, two times a week. Using 60 sec rest between sets will really train the ATP and neurological systems to their maximum. Using longer rests between sets (2-5 mins) will simulate competition conditions. To understand your athletes power output you need to add up the total weight lifted and the total time. E.g. 3 x 3 @ 100kg = 900kg. Each set is about 12 sec (4 sec per lift) with 2 x 1 min rest. So over a total of 2m36s 900kg was lifted at a rate of 346kg/min. This figure relative to body weight is a great guide to your athletes fitness and power capabilities.
JS – What do you think of endurance bounding? (Over 30 meters)
SH – This is a plyometric session all of its own. Only to be done when the legs are fresh and rested for 72 hours. I watched Stefan Holm do this over 60m using 17 -18 bounds, on an indoor athletics track. I use upto 10 bounds in most plyometric programmes in combination with other exercises. You need to be incredibly robust to do 17 – 18 bounds, and consistent too.
Most athletes are not robust enough to do this in combination with other exercises. This does not mean they are not good performers in track and field. The surface you do this on is of major importance like any plyometric exercises, soft and responsive tracks are the best, or real grass to start with. Putting greens and firm fairways are perfect surfaces to bound on but most golf clubs won´t allow it. Let me know of you find one Joe!