Can you give me any info on the benefits of training on the sand rather than on hard surface. Physiologically what benefits and disadvantages would there be.
Training on a hard surface (like a track) and in the sand (the beach) have there differences. Some people do not like to vary their workout surfaces very much. Comfort and habit tend to drive us along into a stale routine at times. So, a break in routine by using different surfaces is great for change in training stimulus and still maintain training specificity.
If the person doing the work is competitive or a recreational participant will influence how much sand time they may want to participate in. Running in the sand increases the effort level significantly. Anyone who has ever walked in the sand can feel the impact, running just amplifies it. If you are training people with fitness goals they are usually more motivated than people with health goals. This motivation will make a difference on training duration's and frequencies.
Training in the sand changes a few things. First, the mechanics of a sand run are modified. The stride gets shorter, the push off phase is exaggerated increasing the level of effort placed on the upper leg and hips. Some people find their lower backs, hips, knees or ankles hurting after a short time period. This may be due to the foot instability created from the sand. The ripple effect sends that shifting around up the chain to the most vulnerable joints. Cardio- pulmonary stress is obviously very high. If you expend energy against an object that moves(the sand) it will take allot more effort to move forward. And, if you are trying to move with a distance or time frame in mind then the training stress can get extremely high. I would recommend limiting the sand to 1 training per. week to see how everyone reacts to it.
The track is probably one of the best, hard surfaces, places to work out. It is a flat, even and stable surface. It does not change people's mechanics and you do not have some unusual load placed on their joints and minds. Obviously, speed work will increase the intensity value while on the track. The usual physiological consequences will follow when applying any elevated training program to your client's.
Sand is great for improving leg strength in a very specific training mode, gives your client's some variety, but can cause excessive stress to the joints and cardio-pulmonary system. The track is great for improving speed, stride length and measurable distances for interval training, but can be boring for some people. Trying all surfaces and segments of run training may be the best possible combination. I hope this helps you with your training.