There could be a correlation between negative emotions, such as anger and hostility, and muscle strength (Tolea et al., 2012). This, however, is a post-hoc examination around the relationship between personality traits and muscle strength and may not infer that 'body strength' actually increases during anger and hostility.
"In spite of the evidence for relationships between personality,
physical activity, and muscle strength, to our knowledge, only one
study reported on the association between personality and muscle
strength (Jorm et al., 1993). In that study, Jorm and colleagues
investigated correlations between neuroticism and extraversion and
muscle strength in a sample of older community-dwelling Australian men
and women. Neuroticism but not extraversion was found to negatively
correlate to strength in women only."
A study conducted on physical performance and anger could support that there are positive correlations between anger and physical performance (Davis et al., 2010). Note that this only focuses on physical performance and does not necessarily indicate that anger directly increases actual body strength (i.e. cardiovascular, resistance level, power).
"Consistent with previous research (e.g., Woodman et al., 2009), anger
facilitated performance of the peak force task. The signiﬁcant
inﬂuence of trait anger and anger-out on physical performance provides
additional evidence of the role of anger’s action tendency in
performance (Smits et al., 2004). This ﬁnding supports Lazarus’s
(2000b) proposed inﬂuence of anger on performance; that is, the action
tendency of anger appeared to align with the task demands and
performance was facilitated by the induction of anger."
This may well tie well in addressing your question:
P1. There is evidence to show that anger facilitates performance of a peak force task.
P2. Breaking a brick involves a peak force task.
P3. X is angry and required to break a brick.
C. It is likely that anger would facilitate X's need to break the brick.
As for anger regulation, the same article touches upon the significance of anger regulation strategies towards anger and physical performance. My intuition would be to say that a response such as anger is more likely to help one "break a brick" when ordered rather than being in a controlled state. Anger is more likely to increase reactive motor skills which could maximise power exerted. I'm not an expert on physical fitness but emotional states of mind would seem to impact physical behaviours in my view.
- Toleaa, M.I., Terracciano, A., Simonsick, E.M., Metter, E.J. & Costa
Jr., P.T. (2012). Associations between personality traits, physical
activity level, and muscle strength. Journal of Research in
Personality, 46, 264-270
- Davis, P.A., Woodman, T. & Callow, N. (2010). Better out than in: The
inﬂuence of anger regulation on physical performance. Personality and
Individual Differences, 49, 457-460