Failure training can provide hands on experience with muscle fatigue. At a certain point, whatever muscle group you’re working can’t complete a full rep. But when you feel like collapsing to the floor after an especially demanding workout, that’s central fatigue telling you it’s time to hit the showers. An interesting study published online at ScienceDaily.com helps explain the mechanism involved.

The neurotransmitter serotonin is released during exercise, which helps you keep going. But when serotonin builds up to a certain level, your brain puts the brakes on the feel good effect by shutting down signals to muscles so they won’t continue working. Basically, your brain rewards hard work but protects you from taking it too far. Listen to your body.

You’ve got plenty of options for cardio day. There’s treadmill and trail running, stationary bike and road cycling, lap swimming and jumping ropes. If you’ve got rhythm and a set of drums, a study published in theInternational Journal of Sports Medicine suggests playing rock star can burn a significant amount of calories.

Researchers had 22 young men with drumming experience complete a test that compared rock concert drumming to pedaling a stationary bike. Drumming burned about 623 calories per hour while cycling burned between 20% to 25% fewer calories. Heart rate while drumming averaged 186 beats per minute. For comparison, normal rested heart rate for adults in their 20s is about 100 beats per minute.

True Strength Moment: You wouldn’t perform the exact same weight training routine for longer than 6 to 8 weeks, because you understand that your muscles will have completely adapted to the stress by that point. To make further gains, you need to change up a stale routine and force your muscles to adapt to more sets and reps, greater resistance, a different order of exercises or whatever. Maybe it’s time to apply the same rules to cardio day.

If the empty calories and carbonation of soft drinks are holding you back in the gym, a study published in Diabetologia, the journal of the European Association for the Study of Diabetes, will give you something else to consider. Researchers suggest that consuming just one, or one extra, sugar-sweetened soft drink per day can increase your risk of developing type 2 diabetes by 18% to 22%.

One study involved 350,000 subjects from 8 European countries while another looked at the diets of 12,403 individuals with type 2 diabetes. One extra drink was defined as a 12 ounce soda more than someone who drank one per day, so the increased risk of between 18% and 22% was the same for someone who had 2 sodas per day compared to someone who held intake to just one. The range of this increase fell slightly when caloric intake and body-mass index was factored in. Good thing you have plenty of other options for boosting energy and alertness.

What bodybuilders have known for decades is now common knowledge: Increasing the amount of protein in your diet can support weight loss and weight maintenance. A study published in the Journal of Nutrition Education and Behavior reports that 43% of the women surveyed from a nationally representative sample of 1,824 participants consumed protein to help prevent weight gain. Those who said they lost weight consumed an amount of protein roughly equal to what’s recommended by the 2010 Dietary Guidelines Advisory Committee.

True Strength Moment: The committee’s report, which was produced by the USDA in conjunction with the U.S. Department of Health and Human Services, recommends 0.80 grams of protein per kilogram of body weight per day. So a 140 pound person should try to consume 51 grams of high-quality proteins daily. One way to reach that goal is to start the day with a medium sized egg (5 grams of protein), have a tuna salad for lunch (24 grams per can) and a post-workout shake providing 22 grams of rapidly-digesting whey protein. Prepare your meals using skinless chicken breast or salmon the next day.

After you’ve been stuck at a plateau for a while, you might be tempted to cheat your way to the next level. While you’ll probably be able to manage greater resistance and/or more reps per set by shortening the range of motion, a study published in the Journal of Strength and Conditioning Researchsuggests you’d be better off getting in the habit of maintaining form.

Recreationally active college aged males were asked to lift weights for 8 weeks, followed by 4 weeks of detraining. Some performed the full range of motion while others shortened the range of each rep. Not only did the full range of motion produce the biggest gains in muscle size and strength, subjects who did shortened reps experienced a greater loss of strength during the detraining phase.

True Strength Moment: While a shorter range of motion can help you change up a stale routine and possibly load the bar with enough weight to blast past a sticking point, this study suggests the technique should be applied sparingly. Sticking with it for 8 weeks didn’t work out very well for these research volunteers.