If two skeletal muscles were the same overall length and had the same metabolic properties, but one had sarcomeres twice as long as the other which one would shorten faster under a very light load

The skeletal muscle with the shorter sarcomere length would shorten faster under a very light load.

Explanation:

A sarcomere is the unit of contraction in a striated muscle. Types of striated muscles include cardiac muscles and skeletal muscles.

All striated muscles are connected to the skeleton and the characteristic sarcomeres are functional in creating force and contractility.

The length of muscle sarcomeres affects how much and how fast the muscle contracts. A muscle with a longer sarcomere length, though having greater force, has a shorter range of contraction when compared to a muscle fiber with shorter sarcomere length.

Sarcomeres, are associated with protein fibres; myosin and actin. Myosin binds to actin after a calcium influx. The calcium influx serves to expose the binding sites of actin, enabling both proteins to bind in a cross binding pattern.

the energy generated by an individual's metabolism is calculated in met (metabolic equivalent of task). the met is the ratio of the work metabolic rate to the resting metabolic rate. one met is illustrated as 1 kcal per kilogram per hour, and is probably equal to the energy cost of sitting quietly.

1 met is equal to 1.162 watt per kg

1 kg is equal to 1000 grams

as the person weighs 80000 gm, that is, 80 kg.

therefore, 80*1.162 = 92.96

thus, the person expends 92.96 watts of power while at rest.