Favorite strengthening activities with body weight (in no particular order):
* Front Plank (elbows) or Pedestal (hands) (30 - 60 sec repeated 3-5 times through a 20-30 minute routine). Increase difficulty by using one arm and/or one leg at a time.
* Back Plank (elbows) or Pedestal (hands) (30 - 60 sec repeated 3-5 times through a 20-30 minute routine) Increase difficulty by using one arm and/or one leg at a time.
**** I believe it is crucial to monitor these closely and actively correct improper technique on these planks. Too often they become "hangs" where the hips are anywhere but in a constructive position. *****
* Side Plank/Pedestal (20-30 second/side repeated 3-5 times through a routine). Make sure the hips are forward and the head is kept as far from the feet as possible. Variations include lifting the top leg, slowly swinging the top leg forward and backward, and doing side "dips" (increase the amount of time to 30-60 seconds with dips).
* Push-ups (30-60 seconds repeated 3-5 times in a routine with a focus on proper posture not # of reps). Variations include spiderman push-ups where a knee is brought up near an elbow when going down alternating side each time, or holding for 3-5 seconds in the down position.
* Self-Throw Downs (30-60 seconds repeated 2-3 times through a routine). Keep hips on the floor. Pull toes towards shins. Keep legs reasonably straight. Don't let heels hit floor but come within 2-3 inches of the floor. Don't come up higher than you can without bending your knees. Variations include adding scissor motions at the top and or bottom and bringing legs down slightly to the side
* Three-way leg lifts (3 sets of 10-12 on each leg in three positions -(inverted, neutral, everted.). Lay flat on ground with hips vertical. Similar to side planks keep hips forward, feet as far from head as possible. Keep motions slow and deliberate - try to minimize the role of momentum.
** There are many other activities that I include with any combination of the above to keep things fresh, but they aren't as crucial as the ones above **
We do most of the above activities on aerobic/recovery days.
On harder days where we're tearing down the body with harder runs we do routines that may include:
* Speed rope (500-1500 ground contacts depending on ability and week in the cycle, typically before the run during indoor track season)
* Gambetta Leg Circuit:
http://www.functionalpathtrainingblog.com/2010/12/the-gambetta-leg-circuit.html
Don't advance the kids too quickly through the progression. Most will be sore even at the beginning levels. if you don't do this pre-season (during indoor track), I definitely wouldn't introduced it to them once the outdoor season begins. The combination of this routine and hard workouts is incredibly stressful to young runners and you'll have a bunch of very sore/injured kids without the proper build up. This is done after the hard workout once outdoor track starts. During indoor we usually do this before the harder workouts, but there are logistical issues driving that rather than optimizing benefits of the run training.
* Sumo Squats (1-2 sets with 20-40 reps)
* Single Leg Squats/Water Pumps (focus on moving knee over the big toe - don't let it collapse to the inside or outside). I think I got this from a Scott Simmon's book. Have the runner lift one leg behind them and place on a chair/ledge/etc. or have another athlete hold the foot while they squat with the other leg.
* Single leg hurdle walk overs (forward & backward, 2-3 sets of 10-12 with each leg)
* Leg raises with heel drops (1-3 sets of 20-30 reps) Stand with forefoot on a stair and the back half of the foot hanging over a step. Drop down as low as possible and raise up as high as possible. Do these at a moderate tempo but be deliberate with the motion - under control up and down.
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There are certainly strengthening components in many of the dynamic warm-up activities we do as well. Indoor we often spend many consecutive days emphasizing proper mechanics and what we want to accomplish with each motion. In season, we still do mobility activities/warm-ups/drills almost every day.
We change our routine up a bit each year, again to keep it fresh and to incorporate things we might have learned. Last year what we did was similar to what Dathan Ritzenhein does in this video:
https://www.youtube.com/watch?v=EhzzpZVMtl4
I especially like this video because he's in tights with a red line down the side which makes it very easy to identify motions/positions to the kids.
With regard to A skips and B skips it seems like there's a wide variety of styles. I like the following video with English Gardener (I think) and John Smith:
https://www.youtube.com/watch?v=YFGw5pTcUl4
While most distance runners may not race with anywhere near that level of range of motion, I think there's a beneficial component to strengthening the hip flexor by going through that range of motion.
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I don't believe that there's an optimal routine for a group, but the best routine is the one that is done. Do what you need to as a coach to avoid activities with poor mechanics or that become drudgery. Change things up regularly. Teach a quick routine (10 minutes) as a fall back that's easily memorized and can always be done even when time is short.
As I'm always looking for good ideas, I look forward to reading other ideas...