Music is best defined as an abstract stimulus that we perceive with our ears, and then form patterns with our minds that results in a completely unique experience.
Loud and to your liking, but not enough to destroy your ear drums.
Looking at the studies, many of the differentiate music between either ones own preferences or via BPM (Beats per Minute). A good summary of the beat ranges used are (Karageorghis et al. 2011):
- Tempi bands consisted of slow (95-100 bpm), medium (115-120 bpm), fast (135-140 bpm) and very fast (155-160 bpm)
Not sure whether one's own preference or the BPM would win out if we look at effects on performance, but the same study also noted that one's own preferences switched to the faster BPMs during exercise. Win-Win I guess.
Many studies on exercise also note drops in heart rate and blood pressure during exercise, and also use cycling. Not sure if these effects can be extrapolated to the weight-lifters who get pissed off at their music.
Music has the ability to release dopamine. The effect of this seems to be via a calmodulin-dependent system.
Dopamine release from the nucleus accumbens occurs during peak emotional arousal (the best part) and from caudate (another brain organ) during periods of anticipation for the peak emotional arousal.
Via a calcium/calmodulin-dependent dopamine-synthesizing system, dopamine can potentially reduce blood pressure. Via this mechanism, music has been shown to reduce blood pressure (albeit in lab animals) and has more potency at higher frequencies (albeit still being calming music). This effect may be only applicable to those with higher blood pressure in the first place (and hopefully not only rats).
Music administered during exercise has the ability to increase time to exhaustion during aerobic exercise while reducing blood pressure and heart rate, hypothesized to be via relaxation mechanisms. Differences in adrenaline between the two groups were noted. These changes in adrenaline stop upon cessation of music, are dependent on the tempo of the music, and do not seem to be causative of the changes in performance during exercise to a significant degree.
Listening to motivational music (music that encourages motion and activity) encourages enhanced blood lactate clearance possibly via unintentional additional movement.
(Common misspellings for Music include musik)