Weight lift your way to a better memory

memory enhanced by weight lifting
Image by Westfall via Wikimedia Commons

All forms of exercise are good for your memory. Either single bouts or a long-term habit of aerobic exercise like running and swimming can improve memory. Resistance training like lifting weights, or doing sit ups or push ups, can also give memory a boost. This is pretty amazing because aerobic and anaerobic exercise turn on completely different molecular pathways in the cell, but both can improve memory. Scientists think this is because exercise causes a short term stress response in the body. If someone is stressed during memory consolidation, when the brain turns short term memories into long term memories, it causes stronger memory formation. For example, when people are made to hold a hand in cold water for several minutes after learning something, they are more likely to remember what they learned. This mainly works for episodic memories (memories of people, places, things and contexts) not semantic memories (memories of abstract facts and concepts i.e. general knowledge), and is strongest when the memory has an emotional component. This makes sense because episodic memories are thought to help protect us against threats and dangers – if we remember we saw tigers in the jungle, we are less likely to go there.

When the body is stressed, the brain releases adrenal and noradrenaline which control the fight or flight response, and cortisol, the major stress hormone. Adrenaline and cortisol affect signalling between the amygdala (the area of the brain that processes emotions) and the hippocampus, which coordinates memory formation. This leads to stronger consolidation of emotionally charged memories. Short term and long term increases in cortisol also improve amygdala processing of emotional memory but impair the formation of short term memories in the hippocampus.

In a recent study, people were shown a series of images designed to evoke a neutral, positive or negative emotional response. They were then asked to do weight training (a series of single leg knee lifts) or no exercise and given a recall test. In the test they were shown the same images again and similar images and asked if they remembered seeing each image and if they recollected an emotion associated with each image.

All participants recalled the positive and negative images better than the neutral images. This is because the brain filters out information that we don’t need to remember. One way it does this is by assessing whether or not the information is attached to an emotion. The group that exercised performed better on the recall test than the group that didn’t. But within the exercisers, some people had a higher stress response to the exercise than others. These ‘high responders’ had higher heart rates and blood pressure than the ‘low responders’. The low responders had better recall of neutral items than the high responders. There was no difference in recall of positive or negative images. This supports the theory that exercise-induced stress helps strengthen emotional memories. But it probably won’t help us remember where we left our keys.

The Scientific Paper:

Weinberg et al. A single bout of resistance exercise can enhance episodic
memory performance. Acta Physiologica. 2014

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