Stationary cycling strained the ACL little in 8 knee patients measured in vivo: peak strain ranged from 1.2% (175 W, 90 rpm) to 2.1% (125 W, 60 rpm) across six power and cadence conditions, neither power (75-175 W) nor cadence (60-90 rpm) changed it significantly, and the pooled mean peak of 1.7% was relatively low against other rehabilitation activities tested before

Stationary cycling is often prescribed after ACL injury or reconstruction, but the strain it places on the ligament or on a graft had not been measured. Fleming and colleagues measured ACL strain in vivo in eight patients who were candidates for arthroscopic meniscectomy, under local anaesthesia, while they rode in six conditions: 75, 125 and 175 W, each at 60 and at 90 rpm.

Peak strain ranged from 1.2% at 175 W and 90 rpm to 2.1% at 125 W and 60 rpm. Neither power nor cadence changed peak strain significantly, so the values were pooled across the six conditions: the mean peak strain was 1.7%, which the authors call relatively low against other rehabilitation activities tested earlier.

They conclude that rehabilitation programmes can use this range of power and cadence without significantly changing ligament strain, and that a rider can raise muscle activity with more power or a lower cadence without putting more strain on the ligament or graft.

n = 8 patients who were candidates for arthroscopic meniscectomy. Both sexes, adult to middle-aged, by the PubMed indexing (the abstract states neither). The abstract does not describe the state of their ligaments; since they were meniscectomy candidates rather than ACL patients, their own ligaments were measured, not grafts (our reading).