What makes abstaining from sex to "hold their strength" a myth?
In a Chinese study in 2003, it was proven that the 7th day (without orgasming) men's testosterone levels spike to 145.7% of base level. The 6th day is normal and so is the 8th.
(Citation: Jiang M, Xin J, Zou Q, Shen JW. A research on the relationship between ejaculation and serum testosterone level in men. J Zhejiang Univ Sci. 2003 Mar-Apr;4(2):236-40.)
Testosterone increases sex drive, aggressiveness, and strength.
A man competing on day 1-6 and day 8 would compete normally.
The same man, on day 7 would (all other things being normal) perform better.