A young black man, mad eyed and drenched in sweat, hooks his arm around the neck of another and the pair thrust out their chests in angry intent.

The men are not fighting but krunking a limber and confrontational form of dance which has become incredibly popular among the poor black neighbourhoods of South Central Los Angeles.

David La Chapelle, a Caucasian music video director, has made a film that highlights the striking physicality of the dance and examines the complicated lives of its practitioners.

While La Chapelle obviously struggles with cohering this 90-minute effort after a career working in four-minute blasts, he does gain unparallelled access to the everyday drama of the people involved.

The film credits reformed drug dealer Tommy The Clown with starting the craze. After a jail term, he vowed to put something back into the community he lived in and started up a troupe of dancers, all dressed in clown gear, to perform at children's parties.

Clown dancing had its off-shoot in krunk, which eschewed the panstick, resembling a sort of hip hop mosh-pit with dancers shoving and confronting each other in a frenzy of self-aggrandizement.

Just as Tommy sees his dancing as a power for good, the krunk dancers express their frustrations at their disenfranchised status through dance rather than through gangs or violence.

As one dancer says, there is a choice in a young person's life growing up in these areas: "to dance or be in a gang".

La Chapelle shows affecting motifs within the dancers' routines that echo the violence and oppression they have grown up with.

The director is most successful when just capturing the dancing, which is incredible. The film begins with a text screen message that none of the footage has been speeded up. The dancing is so energetic and gymnastic it takes your breath away.

Best of all is a dance championship between members of the 50-plus krunk gangs that span LA there is even one all Asian group called Rice Track.

A dance-off between Miss Prissy a charming, girl-next-door type and her arch-rival El Nina is tremendous with the former winning by pouring a bottle of water over her head while dancing.

Less successful is La Chapelle's decision to interweave a dance sequence of Prissy, Tight Eyez and Lil C made to glossy pop video production standards.

The dancers are in glitter paint to accentuate their sinewy torsos and their movements have been put in slow motion which only succeeds in negating the kinetic energy of their routines.

There are other rather uneasy moments that suggest that the film is not quite as naturalistic and agenda-free as it makes out.

Claims made by many of the dancers that krunk differs from hip-hop in that it is marginalised and none of its protaganists are in it for fame or reward seem a little disingenuous.

While La Chapelle's film celebrates the underground nature of the genre the director has been one of the main culprits of bringing it in to the mainstream. His video for Christina Aguilera's Dirrty single featured many of the artists in Rize.

Chapelle also undermines his own attempts at naturalism by not using the source music at the dances he films.

Still the time spent in LA's projects by La Chapelle in the making of the film brings to light the dangers the residents dance to escape from.

We see big, amiable Tommy break down in tears when he learns that robbers have broken into his home and looted it while he was away at the dance championship.

Elsewhere a 15-year-old krunk fanatic is shot dead in the street on the way back from buying an ice lolly.

These moments hit a depth that the film rarely repeats but the dancing is enough to merit a trip to the cinema for Rize.