I do 4 days/week of core/strength work - ~20mins/day before work, with 4 different routines. I always do a "circles" warmup first - 8 circles in each direction for wrists, neck, arms (from elbow, then from shoulder), shoulders (shrug/circle fwd & back), torso (move upper body in circle around hips), hips (circle hips around stable shoulders).
Monday: bodyweight stuff mostly, plus some kettlebell swings. Steam engine, speed skater, mountain climber, fire hydrant w/rear extension, forward leg raise, hip internal rotation, pushups.
Tuesday: lift heavy. Squats, deadlifts, box step-ups/lunges/split squats, adductor lifts, 90* leg raise (lying on side: targets gluteus medius), leg extensions, planks.
Wednesday: upper body day. 1-arm kettlebell swings, kettlebell snatches, bent-over row, overhead press (or clean & press), Y/T/W/L on a swiss ball, forward & lateral arm raises, pushups, rotator cuff, trunk rotation, lat pulldowns and internal shoulder rotation with a band. Also: side steps w/band (gluteus medius again), hip internal rotation.
Thursday: core stuff with swiss ball. Pot stirs, rollouts, back extensions, bridges, hamstring curls, Russian twists, overhead pass. Also clamshell (gluteus medius again) and adductor lift.
Targeting the gluteus medius and adductors/internal hip rotator muscles daily has cleared up a lot of niggles I used to get once running mileage really ramped up. During taper weeks I tend to do bodyweight work only and add in foam rolling and yoga for mobility.
__________________________________________________________ ill advised racing inc.