Injuries may be related to the type of grass used on sporting fields. In Australian football, with respect to
ACL injuries, there are long-standing statistically-significant biases towards
more injuries in the early months of the season and on grounds that are further
to the north of Australia (in warmer climates). The early-season bias for ACL
injuries also exists for natural grass surfaces in the NFL (American football) competition. There is
an early-season ACL bias for the NFL on Astroturf surfaces in open air
conditions but not on Astroturf surfaces in closed arenas. There is also no
‘southern’ or warm-climate bias demonstrated in the NFL. Further analysis of
Australian football reveals that the risk of ACL injury is significantly lower
on grounds that have perennial ryegrass as the major species, compared to
bermudagrass. This explains both the warm-climate and early-season biases. There
is only a minimal correlation between hardness, as measured on natural grass
fields by the penetrometer, and ACL injury risk in Australian football.
Perennial ryegrass, compared to other common turfgrass species such as
bermudagrass, Kentucky bluegrass and annual bluegrass, generally leads to
surface conditions with reduced shoe-surface traction. This is because perennial
ryegrass produces less thatch and has fewer rhizomes (or stolons) which may
create excess friction between the shoe cleats and grass layer. The use of
perennial ryegrass is the best explanation for the lower ACL injury rates in the
southern parts of Australia. The early-season bias exhibited in all examined
competitions played on natural grass is likely to be related partly to the
increased predominance of ryegrass in the latter stages of the season and partly
to the decrease in thatch and lateral growth due to traffic during the season. Shown below are examples of the common types of grass used in Australian sports fields:
Couch (Bermuda) grass
Couch (Bermuda) grass
Couch (Bermuda) grass
Rye grass
Rye grass
Rye grass
Kikuyu grass
Poa annua
Modular system to lay grass
Field turf (artificial blades in soil)
Bare area of mud
Click to download the following .pdf papers researching the role of ground and grass conditions and injury in football:
