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Every week or so, we'll be asking one of the Best Life experts for advice on diet and exercise, ways to get better rest and strategies to live a little younger.

If you have a question, send it to us!

Q: Ask Bob Greene's Team: I only have 30 minutes to work out. How should I use them?

We asked Michelle Kennedy, MS, Best Life fitness expert, to give us four examples of 30-minute workouts:

*A CrossFit-type workout: This routine on the Best Life blog, modeled after CrossFit, involves doing a series of intense exercises, like mountain climbers and squats, as fast as you can in a fixed amount of time.

*Half-and-half: 15 minutes of steady-state cardio like running or bicycling, and 15 minutes of strength training exercises that include Bob Greene's Basic Eight moves.

*High-intensity intervals: In short cardio workouts like these, you alternate sprints and recovery for short periods of time.

*Long sprints: Warm up for five minutes, then run, bike, swim or Rollerblade at top speed for 20 minutes, and cool down for another five.
 
Can you guess what Kennedy recommends as the best workout for those who are pressed for time?


Kennedy says that CrossFit is the winner for those who are trying to increase their general fitness and lose weight (as opposed to training for a race or competition). "This type of workout gets your heart rate way up and gives you the benefit of doing different exercises every day so you don't risk injury due to overuse." What's more, moves like mountain climbers and dumbbell squats target multiple body parts at the same time, giving you more bang for your energy buck.

Runner-up: the half-and-half workout. The CDC recommends muscle-strengthening activities on at least two days a week, but Kennedy says that when women are crunched for workout time, weights are usually the first thing to go. "Regular weight training should be a part of your fitness plan, as toned muscles help you burn extra calories, strengthen you to do typical daily activities (lifting, pushing, pulling) and protect against aging by preventing the loss of muscle and bone."

Read more about the benefits of strength training

Next on the list: cardio intervals. "Research suggests that these 30-minute interval routines can help you lower your risk for diabetes and even get rid of some belly fat," says Kennedy. However, you'll still need to find some extra time during the week to squeeze in weights. Another reason to mix up your routine:  Doing all cardio all the time is inefficient —even if you swear to max out during your workouts. Kennedy says that it's very hard for nonathletes to stick with sprints that are longer than five minutes. "Your rest periods will end up being longer than your sprints."