

Effect of exercise is different with depth forward bend.
With deeper forward bend is effect forwarded on centre of thorax.
Second factor is position of arms before thorax. With arms higher before thorax is effect on upper part of pectoralis.
Primary:
m. pectoralis major - sternal part
Secondary:
m. pectoralis major - clavicular part
m. deltoideus - front part

With cross arms is bigger strain in pectoralis and effect of exercise is bigger too.