Now, if they are unsteady on their feet, it is because of encroaching old age. The climax of the National Music Festival this weekend features three acts who were all in the charts more than 30 years ago - Bob Dylan, The Who and Eric Clapton.
One comfort for the performers is that their audience grows old with them. This weekend's extravaganza will see the largest number of corporate hospitality packages ever at a British rock concert. For pounds 200 upwards, concert-goers can be guaranteed a nearby luxury hotel room after the gig, so that they can have a lie down after the afternoon's exertions.
The performers are likely to resort to less blatant tricks. Renewed demand for those too young to die and too old to rock'n'roll without an intermission means that rock concerts today are increasingly resorting to secret formulae to disguise the over-50s' lack of stamina.
The Unplugged phenomenon has, of course, been a godsend. Astute publicity claiming that acoustic based sets reveal hidden charms of the music do not mention that they also provide a stool for the performer.
Another trick is a solo spot for a non-singing member of the band. Mick Jagger left the stage midway through The Rolling Stones' shows in the recent world tour to allow Keith Richards to sing almost his entire repertoire - and to allow Mick to have a sit down.
Being a pianist, of course, is an inestimable boon for resting the legs. Paul McCartney in his shows spends longer at the keyboards than he ever did in the Sixties. Little Richard celebrated his 60th birthday on stage at Wembley not long ago and was athletic enough to play the piano with his feet; but that was the most exercise his feet had all night.
Intervals are now de rigeur. As the Pink Floyd shows demonstrated they serve the dual purpose of giving the band a rest and exploiting 30 years of merchandising memorabilia.
Bob Dylan plays regularly, but his one-hour afternoon performance on Saturday will mean that he will be seen for the first time in years.
Normally when he is on tour the lighting is on fade to black so that the condition of his face has been a matter for conjecture. Hyde Park could prove his undoing. The afternoon sun can be cruel.