scotsman

good question but unfortunately I don't think there's a simple answer as the term "energy" is very vague.

Physiologically, the lack of energy you experience after a stressful day is different from the lack of energy you experience after hard physical work.

Exercise has acute and simultaneous effects upon fuel metabolism, hormone responses and the central nervous system. I would guess that the effects you experience at the end of a 1 hour spinning class are probably at the level of the nervous system, but partly associated with changes in circulating hormones/fuels. For example you might also get your energy back if you were suddenly required to fly a jet, even if you were sitting still, so mental stimulation might be a part of it.

Over the long term, exercise improves your ability to deal with both physical and mental stress (by reducing cardio responses and responses mediated via nervous /endocrine system which can make you feel "tired")

I think rather than "giving energy", exercise, esp. aerobic exercise, preventa the loss of energy associated with stressful, sedentary lifestyles.

that's my understanding at least

it's a cheap Polar model, I assume it's measuring the average over 3-5 secs and calculating HR per min on that. The dizziness also kicks in about 6-10 secs after lift, not right after.

I've actually noticed that my pulse is highest about 10 secs after lift. I always do cardio after weights, and have pulse montior on, and just out of interest have looked at pulse during squats/leg press. I'm taking a weight that I can max about 8 reps on.

Of course the pulsemonitor takes a few seconds to register change in pulse, but during (can see it on leg press) the pulse doesn't get too high (110-130), then shoots up to around 160 10 secs after). The lift takes about 40 secs total.

but no idea whether it's oxygen debt or stimulation of autonomic nervous system, I'd assumed it was former

thanks for help Michael. As my ear drum ruptured during the lift, I'd also like to know if I can reduce the sky-high blood pressure, I've read that systolic values over 300 can be reached during squats.

sorry but I think it would be painful for you to read my danish, but I can read it.

does anyone know how to reduce the large increase in blood pressure during squats. Even when I try to breath properly I almost faint afterwards, which I can live with, but I also just perforated and ear-drum, which I can't live with.

any advice much appreciated.