A good old 1981 paper on squat training and detraining after a 24 weeks intervention. (Link to article).
Showed elite group of weightlifter showed a huge improvement in squat training (30%). As soon as they stopped squatting and training there was a rapid strength decline loosing about 15% of there strength over a 4 weeks period, however this decrease plateau for another 4 weeks at a level there still significant higher than pre intervention.
A experimental group trained with barbells three times per week with a program consisting mainly of dynamic squat exercises about 75% of the
contractions were concentric, and 25% was eccentric.
The training. was progressive with weekly increasing loads (80-100% concentric and 100-120% eccentric of 1 RM) and an increasing number
of lifts (16-22 per exercise).
The concentric contractions included one to six repetitions per set and the eccentric contractions of one to two repetitions per set (3-4 s in duration). The training period lasted 16 weeks and was follow by a 8-week detraining period, therefore the total duration being 24 weeks.
To prevent injuries and make the training program more interesting, light concentric exercises for the trunk, arms, and legs were included in each training session. During the detraining period strength training was terminated totalily, but the subjects maintained their normal daily activities.