The best replacement for running is walking.

The best alternatives to running are rated as following:
★★★★★  walking
★★★★  biking
★★★  jogging
★★★  cycling
★★★  swimming
★★★  elliptical
★  walking calories
★  spinning
★  walking shoes
★  training shoes
★  insanity
★  treadmill
★  sprinting
★  weight lifting
★  rowing
★  lifting
  jump rope
  walking to lose weight
  crossfit
  outdoor running
  lifting weights
  jogging speed
  weight training
  walking in the rain
  weightlifting
  hiit
  bicycling
  cross training shoes
  yoga
  squats
  skipping
  elliptical machine
  swimming better
  jogging pace
  biking calories burned
  walking calories burned
  biking for weight loss
  jumping
  biking and weight loss
  biking better
  incline walking on treadmill
  stairs
  cross country skiing
  rollerblading
  swimming for calorie burn
  jumping rope

Your alternative for running is not listed? Suggest!
Speaking about running, one probably shouldn't forget about plantar fasciitis.

Other search terms related to running and their ratings are:
★★★★★ plantar fasciitis
★★★★★ losing muscle
★★★★ knee pain
★★★ shin splints
★★ heel strike
★★ limits
You have in mind a companion for running and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of running in all years. Click on graph for more.
running
walking
biking