The efficiency of human muscle has been measured (in the context of rowing and cycling ) at 18% to 26%. The efficiency is defined as the ratio of mechanical work output to the total metabolic cost, as can be calculated from oxygen consumption. This low efficiency is the result of about 40% efficiency of generating ATP from food energy , losses in converting energy from ATP into mechanical work inside the muscle, and mechanical losses inside the body. The latter two losses are dependent on the type of exercise and the type of muscle fibers being used (fast-twitch or slow-twitch). For an overall efficiency of 20 percent, one watt of mechanical power is equivalent to kcal per hour. For example, one manufacturer of rowing equipment calibrates its rowing ergometer to count burned calories as equal to four times the actual mechanical work, plus 300 kcal per hour,  this amounts to about 20 percent efficiency at 250 watts of mechanical output. The mechanical energy output of a cyclic contraction can depend upon many factors, including activation timing, muscle strain trajectory, and rates of force rise & decay. These can be synthesized experimentally using work loop analysis .
“Reg Park’s theory was that first you have to build the mass and then chisel it down to get the quality; you work on your body the way a sculptor would work on a piece of clay or wood or steel. You rough it out””the more carefully, the more thoroughly, the better”” then you start to cut and define. You work it down gradually until it’s ready to be rubbed and polished. And that’s when you really know about the foundation. Then all the faults of poor early training stand out as hopeless, almost irreparable flaws. [..]
Of concern to any user of Winstrol during a cycle should be its intoxicating effect on the liver . The drug is a 17aa structured steroid , meaning it has been structured in a way which allows it to be orally bio-available, yet this has the negative effect of making Winstrol potentially harmful to the liver. It is therefore paramount the duration of a Winstrol cycle is limited, the dose of the drug is not excessive, the user does not stack it with other hepatotoxic compounds, does not drink alcohol whilst on cycle, and does not use Winstrol if they have an underlying medical condition which effects the livers health. There are supplements available which also help protect the liver (Milk Thistle, Liv-52 etc), and these would be advisable during any Winstrol cycle .