This link below is interesting as it tells us about research that advocates a 6 second blast for older people being beneficial vs normal exercise.
"A pilot study involving 12 pensioners showed going all-out in very short bursts, reduced blood pressure and improved general fitness over time." (BBC News 2014).
This type of rapid burst of activity and its benefits were the subject of an Horizon documentary about 2 years ago. A BBC reporter used this and had a minor stroke but we will ignore that.
I think this looks interesting and worth following up. The shock to the system probably blasts the cob-webs!