Does Tightening Stomach Muscles Work Out Abs at the Desk?

If you want to help make up for all of those hours sitting on the job, tightening your stomach muscles at your desk can provide some benefits. Although the activity won't replace a full workout session, performing simple muscle contractions can help maintain lean tissue and burn some extra calories. These exercises aren't safe for everyone though, so talk to your doctor if you're currently inactive or have any health conditions.

When you tighten your stomach muscles without bending any joints, you are performing isometric exercise. In contrast, situps or crunches are isotonic exercises because you bend at the waist, causing muscles to lengthen and shorten. Muscles remain the same length during isometric exercises and as result, the toning benefits are limited, according to MayoClinic.com. Isometric exercises can be effective at preventing muscle loss -- which you may be vulnerable to if you're sedentary throughout the day -- but they won't build much new tissue.

Beyond muscle toning, isometric exercise can help you burn more calories, making weight management easier. Don't expect miracles, though -- to lose 1 pound of fat, you must burn 3,500 more calories than you consume. During 30 minutes of isometrics-based Hatha yoga, a 155-pound person burns just 149 calories in 30 minutes -- and you're unlikely to contract your stomach muscles for a full half hour. For the best results, try to move around as much as possible at work; shake your leg, tap your fingers and fidget as much as possible in addition to the occasional stomach-tightening session. This can help you burn up to 20 percent more calories throughout the day, according to the American Council on Exercise.

During isometric exercise, your body creates a large amount of muscle tension in a short time span, which may result in a dramatic spike in blood pressure. Therefore, Harvard Medical School reports that these types of exercises are not usually suitable for people with high blood pressure or other heart issues.

Although most healthy people can safely perform isometric exercises, the best way to achieve a lean, toned physique is to base your strength-training routine on isotonic moves. For proper balance, target all major muscle groups two to three times per week, allowing 48 hours of recovery in between. Choose a variety of exercises and equipment; for example, use dumbbells and weight machines in addition to performing body-weight exercises such as pushups and pullups. A complete workout program also includes cardiovascular exercise such as walking, running, cycling or swimming at least 150 minutes per week, with each cardio session lasting at least 10 minutes.