Light-Headedness & Weakness During Workouts

Listen to warning signs from your body during a workout.
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There’s nothing like a good workout to challenge your physical capabilities. When you’re forking out the effort required to reach your goals, you’re asking a lot of your body and you’re entitled to feel put through the wringer. However, feeling weak and light-headed may be indicators that there’s an imbalance somewhere in your training that you can seek to fix.

Level of Exertion

Working out at too high an intensity can easily cause light-headedness and weakness as the heart rate is pushed to a level beyond safe exercise parameters. When it comes to cardiovascular, or cardio, training and conditioning, heart rate is one of the best tools to determine whether you’re working out within safe limits for your ability and your body. The Cleveland Clinic recommends working out within a target heart rate zone between 60 and 80 percent of your maximum heart rate. Pushing the limits above 80 percent is permissable in certain interval-training workouts but is not recommended without an established level of cardio conditioning and experience. Weakness may result from possible hyperventilation and the general inability to take in enough oxygen.


Sometimes a swig of cold water tastes yummier than anything else in the midst of an intense workout. Water is rarely ever a bad thing, and light-headedness and weakness may be your body letting you know you’re not getting enough of it. Whether you’re sweating it out in a cardio session or throwing weights around in your strength-training routine, physical exertion raises the body temperature and produces sweat to keep you cool. Feeling light-headed and weak can be warning signs of heat exhaustion, indicating that your internal cooling system is failing and needs fluids. If you’re feeling thirsty, then you’re already depleted and should rehydrate as soon as possible. The American College of Sports Medicine recommends consuming 8 to 12 fluid ounces at least 15 minutes prior to exercise and to keep swigging 3 to 8 fluid ounces during exercise for every 15 to 20 minutes of exertion. But you’re not done hydrating even when you’re done with your workout. Be sure to keep hydrating even after exercise to restore your fluid and sodium levels within two hours of completing your workout.


It may sound obvious, but remembering to breathe is a key part of an effective workout. Irregular breathing, hyperventilating or holding your breath can quickly cause light-headedness and resulting weakness. Maintaining a controlled breathing cadence helps keep the heart rate down during cardio activity and makes more efficient use of full lung capacity. During any strength-training routine, be sure to exhale during the point of greatest exertion. It’s not unusual to want to hold your breath when the work is the hardest, but exhaling actually helps move the weight more efficiently as opposed to holding on to muscle tension.


Beyond these possible factors, there may be numerous other reasons for experiencing light-headedness and weakness during a workout, including reactions to certain medications or physiological responses to particular cardiovascular or respiratory conditions. Be sure you have medical clearance to work out prior to beginning any exercise regimen, and seek medical advice if light-headedness and weakness persist.

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