Caffeine
What class of ergogenic aid is caffeine?
Caffeine is a central nervous system stimulant
Which creatine formulation has the strongest scientific evidence?
Creatine monohydrate.
Which compound increases in skeletal muscle following beta-alanine supplementation?
Carnosine.
which gland produces it?
pituitary.
Which compound in beetroot juice is primarily responsible for its proposed ergogenic effects?
nitrate.
Explain how blocking adenosine receptors can influence alertness and perceived fatigue.
Adenosine normally promotes sleepiness and reduces neuronal excitability. Caffeine antagonizes adenosine receptors, reducing these inhibitory effects and potentially increasing alertness and lowering perceived effort.
How does phosphocreatine help regenerate ATP during maximal exercise?
Phosphocreatine donates a phosphate group to ADP through the creatine kinase reaction, rapidly regenerating ATP.
How does carnosine help maintain muscle function during demanding exercise?
Carnosine accepts hydrogen ions and acts as an intracellular buffer, helping limit the decline in muscle pH.
What type of hormone is GH?
GH is a peptide hormone
What nitrate dose and pre-exercise timing are commonly used to support exercise performance?
Approximately 6–8 mmol, or 370–500 mg of nitrate, consumed 2–3 hours before exercise.
Why do some people recommend waiting at least one hour after waking before consuming caffeine?
When adenosine occupies its receptors in the brain, it promotes sleepiness and reduces neuronal excitability. Caffeine competes with adenosine for these same receptors, blocking its inhibitory effects and increasing alertness.
Why does an increase in body mass during the first week of creatine supplementation not necessarily indicate muscle hypertrophy?
Creatine increases intracellular water, which can contribute to early weight gain. Increased body mass alone cannot distinguish water accumulation from an increase in muscle protein.
What daily dose and supplementation duration are commonly studied for beta-alanine?
Approximately 4–6 g/day for at least four weeks, with consistent intake on both training and rest days.
How does GH increase the availability of fatty acids for energy metabolism?
GH promotes adipose-tissue lipolysis, breaking stored triglycerides into free fatty acids and glycerol.
What role do oral bacteria play in the conversion of dietary nitrate into nitric oxide?
Oral bacteria convert nitrate into nitrite. Nitrite can subsequently be converted into nitric oxide in the stomach and tissues.
A 70-kg athlete plans to use the commonly studied caffeine. Calculate the dose range and state a commonly used pre-exercise timing.
he dose range is 210–420 mg. Approximately 60 minutes before exercise is commonly used, although absorption differs among products.
What is the difference between using creatine with and without a loading phase? Include the doses and approximate durations.
Loading uses approximately 0.3 g/kg/day for 5–7 days, followed by 3–5 g/day. Without loading, taking 3–5 g/day increases muscle creatine stores more gradually, over approximately 3–4 weeks.
What causes the tingling sensation after taking beta-alanine?
Beta-alanine activates sensory nerve pathways in the skin, producing temporary paresthesia. Larger, rapidly absorbed doses are more likely to cause it. The sensation does not indicate increased muscle carnosine or improved performance.
How can GH-related sodium contribute to both edema and carpal tunnel symptoms?
Fluid retention causes swelling and increases tissue pressure. This pressure can compress nerves, contributing to carpal tunnel symptoms and paresthesia.
How can nitric oxide produced from dietary nitrate contribute to cardiovascular health?
Nitric oxide promotes vascular smooth muscle relaxation and vasodilation. This can reduce vascular resistance and contribute to lower blood pressure.
Why can caffeine improve performance in endurance exercise, strength tasks, and cognitive tasks even though these activities have different energy demands?
Caffeine primarily acts on the central nervous system by blocking adenosine receptors. This can increase alertness, influence motor drive, and reduce perceived effort. Because these central processes contribute to different activities, caffeine’s potential benefits are not limited to one energy system.
Why might creatine help support working memory and mental focus during sleep deprivation?
Neuronal activity requires ATP. The creatine–phosphocreatine system supports rapid ATP regeneration and helps buffer cellular energy availability. This may help preserve cognitive performance when sleep deprivation challenges brain energy metabolism.
Besides buffering hydrogen ions, how might carnosine support muscle function through calcium handling and protection against oxidative stress?
Carnosine may increase calcium release from the sarcoplasmic reticulum and increase the contractile apparatus’s sensitivity to calcium, supporting muscle contraction. Its antioxidant actions may also help protect muscle cells against reactive oxygen species (ROS).
Describe the signaling pathway connecting GH binding in the liver to growth-related effects in target tissues.
GH binds its receptor and activates JAK2 and STAT5 signaling, stimulating IGF-1 production. IGF-1 then binds its own receptor in target tissues and activates pathways such as PI3K–Akt–mTOR, influencing protein synthesis and cell growth.
Compare the NOS-dependent and NOS-independent pathways of nitric oxide production.
he NOS-dependent pathway uses nitric oxide synthase to convert L-arginine and oxygen into nitric oxide and L-citrulline. The NOS-independent pathway converts dietary nitrate into nitrite and then nitric oxide.